NCERT Solutions Ganita Prakash Chapter 10 Using tokens for subtraction — Figure it Out
Book page 259 Updated on2026-09-05
Q1.
Try to subtract: – 3 – (+ 5). How many zero pairs will you have to put in? What is the result?
Answer
Start with 3 red tokens. You have to take away 5 green tokens — but there is not a single green token there!
Put in 5 zero pairs (5 green with 5 red). The value is still – 3.
Now the set is 5 green + 8 red.
Take away the 5 green → 8 red are left.
Answer: 5 zero pairs are needed, and – 3 – (+ 5) = – 8.
The three original red tokens plus the five red tokens from the zero pairs make 8 red tokens — the answer – 8.
Shorter way: – 3 – (+ 5) = – 3 + (– 5) = – 8. Subtracting a positive number is the same as adding a negative one, so you go 5 steps further down.
Q2.
Evaluate the following using tokens. a. (– 3) – (+ 10) b. (+ 8) – (– 7) c. (– 5) – (+ 9) d. (– 9) – (+ 10) e. (+ 6) – (– 4) f. (– 2) – (+ 7)
Answer
Expression
Zero pairs needed
Same as
Answer
a.
(– 3) – (+ 10)
10
– 3 + (– 10)
– 13
b.
(+ 8) – (– 7)
7
8 + 7
+ 15
c.
(– 5) – (+ 9)
9
– 5 + (– 9)
– 14
d.
(– 9) – (+ 10)
10
– 9 + (– 10)
– 19
e.
(+ 6) – (– 4)
4
6 + 4
+ 10
f.
(– 2) – (+ 7)
7
– 2 + (– 7)
– 9
The pattern: whenever the tokens you must remove are not there, put in exactly that many zero pairs. Every time, the work ends up being the same as ‘add the inverse’ — which is why that one rule is enough for all subtractions of integers.