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INDIAN PLACE VALUE SYSTEM:
Lakhs│Ten-Thousands│Thousands│Hundreds│Tens│Ones
─────┼─────────────┼─────────┼────────┼────┼────
3 │ 4 │ 5 │ 6 │ 7 │ 8
= 3,45,678 = Three lakh forty-five thousand six hundred seventy-eight
Commas in Indian system: After 3 digits from right, then every 2 digits
1,23,456 (1 lakh, 23 thousand, 456)
10,00,000 (10 lakhs = 1 million)
INTERNATIONAL SYSTEM (for comparison):
1,000 = one thousand
10,000 = ten thousand
1,00,000 = 1,00,000 (one lakh) = 100,000 (one hundred thousand)
10,00,000 = 10,00,000 (ten lakhs) = 1,000,000 (one million)
FACTORS of 24:
24 ÷ 1 = 24 ✓ 24 ÷ 2 = 12 ✓
24 ÷ 3 = 8 ✓ 24 ÷ 4 = 6 ✓
24 ÷ 5 = 4.8 ✗ 24 ÷ 6 = 4 ✓
24 ÷ 7 = 3.4 ✗ 24 ÷ 8 = 3 ✓
24 ÷ 12 = 2 ✓ 24 ÷ 24 = 1 ✓
Factors of 24 = {1, 2, 3, 4, 6, 8, 12, 24}
PRIME NUMBERS (only 2 factors: 1 and itself):
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37...
COMPOSITE NUMBERS (more than 2 factors):
4, 6, 8, 9, 10, 12, 14, 15, 16...
HCF = Highest Common Factor (biggest factor in common)
HCF of 12 and 18:
Factors of 12: 1,2,3,4,6,12
Factors of 18: 1,2,3,6,9,18
Common: 1,2,3,6 → HCF = 6
LCM = Least Common Multiple (smallest multiple in common)
LCM of 4 and 6:
Multiples of 4: 4,8,12,16,20...
Multiples of 6: 6,12,18,24...
LCM = 12 (first common multiple)
TYPES OF ANGLES:
Acute angle Right angle Obtuse angle
(less than 90°) (exactly 90°) (more than 90°)
/ | \
/ | \──
/ └──
30°, 45°, 60° 90° 120°, 150°
Straight angle = 180° (straight line)
Reflex angle = more than 180°, less than 360°
Complete angle = 360° (full rotation)
TRIANGLES:
Equilateral: all 3 sides EQUAL, all angles = 60°
Isosceles: 2 sides equal, 2 base angles equal
Scalene: all 3 sides DIFFERENT, all angles different
Right-angled: one angle = 90°
QUADRILATERALS:
Square: all sides equal, all angles 90°
Rectangle: opposite sides equal, all angles 90°
Rhombus: all sides equal, opposite angles equal
Parallelogram: opposite sides parallel and equal
Trapezium: one pair of parallel sides
PERIMETER = total boundary length (add all sides)
Square: P = 4 × side
Rectangle: P = 2 × (length + breadth)
Triangle: P = side1 + side2 + side3
AREA = surface covered
Square: A = side × side = side²
Rectangle: A = length × breadth
Examples:
Rectangle: l=8cm, b=5cm
Perimeter = 2×(8+5) = 2×13 = 26 cm
Area = 8×5 = 40 cm²
Square: side = 7cm
Perimeter = 4×7 = 28 cm
Area = 7×7 = 49 cm²
LETTER WRITING:
Informal Letter (to friend/relative):
─────────────────────────────────────
[Your address]
[Date]
Dear [Name],
[Opening: How are you?]
[Body: Main content]
[Closing: Take care, looking forward...]
Your friend/lovingly,
[Your name]
Formal Letter (to authority):
─────────────────────────────────
[Your address]
[Date]
The Principal,
[School name]
Subject: [Topic in one line]
Respected Sir/Madam,
[Body]
Yours sincerely,
[Name]
ACTIVE: Subject does the action
The dog bit the boy.
(Subject=dog, does biting action)
PASSIVE: Subject receives the action
The boy was bitten by the dog.
(Subject=boy, receives biting)
FORMULA:
Active: Subject + Verb + Object
Passive: Object + was/were + Past Participle + by + Subject
More examples:
She wrote the letter. (Active)
The letter was written by her. (Passive)
They clean the street. (Active)
The street is cleaned by them. (Passive)
SQ3R METHOD for reading comprehension:
S = SURVEY → Look at title, headings, pictures first
Q = QUESTION → Make questions from headings (What is this about?)
R = READ → Read carefully, looking for answers
R = RECITE → Say/write key points without looking
R = REVIEW → Check answers, re-read unclear parts
Finding MAIN IDEA:
Main idea = what the whole paragraph is about
Supporting details = facts that explain the main idea
Topic sentence (usually first): tells main idea
Supporting sentences: give details/examples
Concluding sentence: wraps up the paragraph
MAP SYMBOLS (Legend/Key):
─── Road ═══ Railway line
～～ River ▲ Mountain
□ Building ● City/Town
✈ Airport ♦ Temple
+ Hospital ☆ Capital city
COMPASS DIRECTIONS:
N (North)
│
W (West)─┼─E (East)
│
S (South)
Intermediate: NE, NW, SE, SW
SCALE: "1 cm = 100 km" means 1 cm on map = 100 km in reality
Distance on map × scale = actual distance
DESERT ADAPTATIONS:
🌵 Cactus (plant):
● Thick stem stores water
● Waxy coating prevents water loss
● Thorns instead of leaves (reduce water loss)
● Deep/wide roots to absorb max water
🐪 Camel (animal):
● Hump stores fat (energy reserve, not water)
● Can drink 100+ litres at once
● Wide padded feet for sand
● Long eyelashes protect from sand
● Nostrils can close during sandstorm
AQUATIC ADAPTATIONS:
🐟 Fish:
● Gills extract dissolved oxygen from water
● Streamlined body reduces water resistance
● Fins for steering and balance
● Scales protect body
🐋 Whale (mammal in water):
● Holds breath (no gills, has lungs)
● Blubber (fat layer) for insulation in cold water
● Paddle-like limbs for swimming
MOUNTAIN ADAPTATIONS:
🦅 Eagle:
● Wide wings for soaring in mountain air
● Sharp eyesight to spot prey from high up
🐑 Snow leopard:
● Thick fur for warmth
● Wide paws act as snowshoes
● Long tail for balance on steep slopes
WHY CONSERVE?
FOREST IMPORTANCE:
● Produces oxygen (lungs of Earth)
● Controls rainfall (evapotranspiration)
● Home for wildlife (biodiversity)
● Prevents soil erosion
● Provides timber, medicines, food
THREATS:
● Deforestation (cutting trees for farms/cities)
● Poaching (illegal hunting)
● Pollution (air, water, soil)
● Climate change
WHAT WE CAN DO:
✓ Plant trees (one per birthday!)
✓ Save water (turn off tap while brushing)
✓ Reduce plastic use (use cloth bags)
✓ Save electricity (switch off when not needed)
✓ Compost kitchen waste (avoid burning)
✓ Say no to crackers (air pollution)
संज्ञा (Noun) — नाम बताती है:
व्यक्तिवाचक: राम, भारत, दिल्ली (specific names)
जातिवाचक: लड़का, पेड़, गाय (common nouns)
भाववाचक: खुशी, दुख, ईमानदारी (abstract)
सर्वनाम (Pronoun) — संज्ञा की जगह:
मैं, तुम, वह, हम, आप, वे, यह, ये
विशेषण (Adjective) — संज्ञा की विशेषता बताता है:
बड़ा घर, लाल गुलाब, तीन किताबें, मीठा आम
क्रिया (Verb) — काम बताती है:
खाना, पीना, जाना, आना, पढ़ना, लिखना, दौड़ना
वाक्य उदाहरण:
राम (संज्ञा) मीठा (विशेषण) आम (संज्ञा) खाता है (क्रिया)।
वह (सर्वनाम) तेज (विशेषण) दौड़ता है (क्रिया)।
अनौपचारिक पत्र (to friend):
─────────────────────────────
[पता]
[दिनांक]
प्रिय मित्र/दोस्त,
मुझे खुशी है कि तुम अच्छे हो।
[मुख्य विषय]
तुम्हारा मित्र,
[नाम]
औपचारिक पत्र (to authority):
─────────────────────────────
[पता]
[दिनांक]
सेवा में,
प्रधानाचार्य जी,
[स्कूल का नाम]
विषय: [one line topic]
महोदय,
[विनम्र आवेदन]
आपका आज्ञाकारी शिष्य,
[नाम]
Maths:
English:
EVS:
Hindi:
Class 4 NCERT complete notes — large numbers, fractions, geometry, factors, English grammar, writing skills, EVS topics: maps, adaptation, states of India, conservation with diagrams.
32 pages · 1.1 MB · Updated 2026-03-11
Factors divide a number exactly (no remainder). Multiples are obtained by multiplying. Factors of 12: 1,2,3,4,6,12. Multiples of 3: 3,6,9,12,15... Every number is a factor and multiple of itself. 1 is a factor of every number.
Adaptation is a special feature that helps an animal survive in its habitat. Example: Camel has humps (store fat for energy), wide feet (walk on sand), long eyelashes (keep sand out). Fish have gills (breathe underwater), streamlined body (move in water). These features develop over thousands of years.
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