Math Tricks : Find the value Using common factor / BODMAS Rule etc
Q. Find the value of 237 × 199 -199 × 236
Trick:
Solve: 237×199 - 199×236
Factor out common term 199:
= 199(237 - 236)
= 199(237 - 236)
= 199×1 = 199
Ans: 199
Q. 1999 × 64 + 36 × 1999 = ?
Trick (Using common factor):
→ Take 1999 common:
1999 × (64+36) = 1999×100 =199900
Ans: 199900
Q. [ {40 + (30 + 20)} / 45 ] × 40 − 50 = ?
By BODMAS Rule:
- Solve the bracket first: (30+20) = 50
- Curly braces: 40+50 = 90
- Division: 90/45 = 2
- Multiplication: 2×40 = 80
- Subtraction: 80-50 = 30
Ans: 30
Q) What is the perimeter of a rectangle whose one side is 12 cm and diagonal is 13 cm ?
- Using the Pythagoras theorem:
Other side = Sq Root 13^2−12^2 = Sq Root 169−144 = Sq Root 25 = 5 cm
- Perimeter of a rectangle: P = 2(l+b) = 2(12+5) = 2×17 = 34 cm
Ans: 34 cm
Q) The ratio of length to breadth of a rectangle is 9 : 5. If the breadth is 10 m less than the length, what is the perimeter of the rectangle?
- Let length = 9k and breadth = 5k
- Given: 9k−5k = 10 ⇒ 4k =10 ⇒ k = 2.5
Therefore,
- Length = 9×2.5 = 22.5 m, Breadth = 5×2.5=12.5
- Perimeter: P = 2(l+b) = 2(22.5+12.5) = 2×35 =70 m
Ans: 70 m