NCERT Solutions for Class 4th Maths Chapter 13 Making tables by splitting into equal groups — In-text Questions

Book page 187 Updated on2026-09-19

Q1.

3. Construct other times-tables for numbers from 11 to 20, as you did for 15.

Answer

What to do

Pick a number from 11 to 20, say 12.
Split it as 10 and the rest: 12 = 10 + 2.
For each step, find n × 10 and n × 2, then add them.

Sample answer: the times-12 table

n	n × 10	n × 2	n × 12
1	10	2	12
2	20	4	24
3	30	6	36
4	40	8	48
5	50	10	60
6	60	12	72
7	70	14	84
8	80	16	96
9	90	18	108
10	100	20	120

Times-12: 12, 24, 36, 48, 60, 72, 84, 96, 108, 120

Do the same for 11 (10 + 1), 13 (10 + 3), 14 (10 + 4) … up to 20 (10 + 10).

Why it happens: Splitting off the 10 turns a hard table into the times-10 table plus a very small table.

Q2.

4. As you compared the times-5 table with the times-15 table, compare the times-1 table with the times-11 table, the times-2 table with the times-12 table, and so on. Share your observations.

Answer

Sample answer: times-1 and times-11

Times-1	Times-11	Difference
1	11	10
2	22	20
3	33	30
4	44	40
5	55	50
6	66	60
7	77	70
8	88	80
9	99	90
10	110	100

What we notice

The difference is always the times-10 table: 10, 20, 30, 40 …
The same thing happens for 2 and 12, for 3 and 13, and so on.
So we can write: n × 12 = n × 2 + n × 10.

Example: 7 × 13 = 7 × 3 + 7 × 10
= 21 + 70 = 91

Why it happens: Every number from 11 to 20 is 10 more than a small number. Taking it n times adds n tens each time.

Q3.

6 × 14 = Double of 6 × 7. Why?

Answer

Tara's arrangement of wheels: 6 rows of 14, split into two equal groups of 7.

14 = 7 + 7
So 6 × 14 = 6 × 7 and 6 × 7
6 × 7 = 42
42 + 42 = 84

Adding a number to itself is the same as doubling it. So 6 × 14 is double 6 × 7.

Why it happens: The picture splits into two equal halves. Each half has 6 × 7 wheels, so the whole has twice that many.

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