NCERT Solutions for Class 5th Maths Chapter 13 Hunting days; choosing a jump size to meet or avoid a friend — Let Us Do (Questions 9–10)
Book page 169 Updated on2026-09-19
Q1.
9. Sher Khan, the tiger, goes hunting every 3rd day. Bagheera, the panther, goes hunting every 5th day. If both of them start on the same day, on which days will they be hunting together?
Answer
They hunt together on day 15, day 30, day 45, day 60 … that is, every 15th day.
The two rows of dots meet only on 15, 30, 45 and 60 — the common multiples of 3 and 5.
Common multiples of 3 and 5 = 3 × 5 = 15, then 30, 45, 60, 75 …
Why it happens: 3 and 5 share no factor except 1. When that is so, the first day they meet is simply 3 × 5 = 15. After that the whole pattern repeats, so they meet again every 15 days.
Check it yourself: 15 ÷ 3 = 5 (Sher Khan's 5th hunt) and 15 ÷ 5 = 3 (Bagheera's 3rd hunt). Both are whole numbers ✓
Q2.
10. (a) In the trail shown earlier, Sher Khan's house is on number 25 and that of Baloo the bear is on number 30. Mowgli wants to meet his friend Baloo the bear but wants to avoid Sher Khan's house. How long (in steps) could each jump be?
Answer
His jump could be 2, 3, 6, 10, 15 or 30 steps.
The jump has to do two things at once: reach 30, and miss 25.
Find the jump sizes that reach 30. These are the factors of 30: 1, 2, 3, 5, 6, 10, 15, 30.
Find the jump sizes that would land on 25. These are the factors of 25: 1, 5, 25.
Cross out any jump size that is in both lists. Cross out 1 and 5.
What is left is the answer. 2, 3, 6, 10, 15, 30.
Jump
Reaches 30?
Lands on 25?
Safe for Mowgli?
1
Yes
Yes
No — he walks right past Sher Khan
2
Yes (2 × 15)
No (25 is odd)
Yes
3
Yes (3 × 10)
No
Yes
5
Yes (5 × 6)
Yes (5 × 5)
No
6
Yes (6 × 5)
No
Yes
10
Yes (10 × 3)
No
Yes
15
Yes (15 × 2)
No
Yes
30
Yes (30 × 1)
No
Yes
Why it happens: A jump size lands on a number only if it is a factor of that number. So Mowgli needs a factor of 30 that is not a factor of 25. The only factors 25 and 30 share are 1 and 5 — and those two are exactly the ones he must avoid.
Smallest safe jump: 2 steps. Mowgli lands on 2, 4, 6 … 24, 26, 28, 30. He hops straight over 25 and arrives at Baloo's house.
Q3.
10. (b) What number of jumps (in steps) he could choose so that he can meet both Kaa, the snake, at 21 and Akela, the wolf, at 35?
Answer
He should jump 7 steps at a time. (A jump of 1 step also works, but it is the slow way.)
The jump must reach 21, so it must be a factor of 21: 1, 3, 7, 21.
The jump must also reach 35, so it must be a factor of 35: 1, 5, 7, 35.
Take the numbers in both lists. 1 and 7.
Choose the useful one. 7 steps.
Factors of 21 → 1, 3, 7, 21 Factors of 35 → 1, 5, 7, 35
Common factors = 1 and 7
With 7-step jumps he lands on: 7, 14, 21, 28, 35, 42, 49, 56 Kaa is met on the 3rd jump, Akela on the 5th
Why it happens: To visit two houses with equal jumps, the jump size must divide both house numbers exactly. That is exactly what a common factor is. Here 21 = 7 × 3 and 35 = 7 × 5, so 7 fits into both.
Check it yourself: Try 3 steps. You reach 21, but then 24, 27, 30, 33, 36 — you jump over 35. Try 5 steps. You reach 35, but you land on 20 and 25, skipping 21.