NCERT Solutions Ganita Prakash Chapter 10 Figure it Out — The Token Model
Book page 257 Updated on2026-09-05
Q1.
Complete the additions using tokens. a. (+ 6) + (+ 4) b. (– 3) + (– 2) c. (+ 5) + (– 7) d. (– 2) + (+ 6)
Answer
Put down the tokens, throw away every zero pair (one green with one red), and read what is left.
Tokens put down
Zero pairs removed
What is left
Answer
a.
6 green and 4 more green
none — all are green
10 green
+ 10
b.
3 red and 2 more red
none — all are red
5 red
– 5
c.
5 green and 7 red
5 pairs
2 red
– 2
d.
2 red and 6 green
2 pairs
4 green
+ 4
Part (c): 5 green and 7 red tokens. Five zero pairs are struck out, and 2 red tokens are left — so (+ 5) + (– 7) = – 2.
Why zero pairs may be thrown away: one press of ‘+’ followed by one press of ‘–’ brings the lift attendant back to where he was. The pair is worth 0, so removing it does not change the value of the pocket.
Q2.
Cancel the zero pairs in the following two sets of tokens. On what floor is the lift attendant in each case? What is the corresponding addition statement in each case?
Answer
Set (a): 3 green tokens and 5 red tokens.
3 zero pairs cancel → 2 red tokens are left (+ 3) + (– 5) = – 2 → the attendant is on Floor – 2 (Video Games)
Set (b): 6 green tokens and 3 red tokens.
3 zero pairs cancel → 3 green tokens are left (+ 6) + (– 3) = + 3 → the attendant is on Floor + 3 (Book Store)
Set (b): three zero pairs are struck out and three green tokens remain, so the attendant is on Floor + 3.
Check it yourself: in set (a) he pressed ‘+’ 3 times and ‘–’ 5 times — two more downs than ups, so he must be 2 floors below the ground. ✔