EN हिं

NCERT Solutions for Class 4th Maths Chapter 9 Counting wheels in tens — Multiples of Tens

Book page 137 Updated on2026-09-19

Q1.
Let us count the number of wheels in tricycles. Number of wheels in 10 tricycles with 3 wheels in each is 10 × 3 wheels = ______ wheels. Number of wheels in 10 more tricycles with 3 wheels in each is 10 × 3 wheels = _______ wheels. Number of wheels in 20 tricycles with 3 wheels in each is 20 × 3 wheels = ______ + _____ = ______ wheels.
Answer
10 tricycles. Each tricycle has 3 wheels.
10 tricycles: 10 × 3 = 30 wheels
10 more tricycles: 10 × 3 = 30 wheels
20 tricycles: 20 × 3 = 30 + 30 = 60 wheels

So 10 × 3 = 30 and 20 × 3 = 60.

Why it happens: 20 tricycles are just two sets of 10 tricycles. Two sets of 30 wheels make 60 wheels.
Q2.
Let us count the number of wheels in cars. Number of wheels in 10 cars with 4 wheels in each is 10 × 4 wheels = _______ wheels. Number of wheels in 30 cars with 4 wheels in each is 30 × 4 wheels = _____ + _____ + _____ = _____ wheels.
Answer
10 cars. Each car has 4 wheels.
10 cars: 10 × 4 = 40 wheels
30 cars = 10 cars + 10 cars + 10 cars
30 × 4 = 40 + 40 + 40 = 120 wheels

So 10 × 4 = 40 and 30 × 4 = 120.

Why it happens: 30 is three tens. Three times the 40 wheels of ten cars gives 120 wheels.
Q3.
Solve the following in a similar way. Share how you found the answers. a) 10 × 6 = ____ b) 40 × 6 = ____ c) 10 × 8 = ____ d) 60 × 8 = ____ e) 6 × 8 = ____ f) 60 × 8 = ____ g) 4 × 6 = ____ h) 40 × 8 = ____
Answer
a) 10 × 6 = 60
b) 40 × 6 = 60 + 60 + 60 + 60 = 240
c) 10 × 8 = 80
d) 60 × 8 = six 80s = 480
e) 6 × 8 = 48
f) 60 × 8 = ten times 48 = 480
g) 4 × 6 = 24
h) 40 × 8 = ten times 32 = 320
Small factTen times bigger
6 × 6 = 3660 × 6 = 360
6 × 8 = 4860 × 8 = 480
4 × 8 = 3240 × 8 = 320
4 × 6 = 2440 × 6 = 240

Knowing the small fact gives the big one at once.

Why it happens: 60 groups are ten times as many as 6 groups, so the answer is ten times as big and a 0 joins at the end.
Q4.
What happens when the number of groups is a multiple of 10?
Answer

The answer becomes the small fact with zeros joined at the end.

6 × 8 = 48  →  60 × 8 = 480
4 × 6 = 24  →  40 × 6 = 240
3 × 4 = 12  →  30 × 4 = 120
Why it happens: 60 groups mean 10 sets of 6 groups. Ten times a number pushes every digit one place to the left and puts a 0 in the ones place.
Was this helpful?