Reasoning · Grade 2-2 The Multiplication Table

Problem

How often a number appears in the table

In the times table with both factors from 1 to 9, count how often a number appears. Order makes a different cell, so unequal factors count twice. For example 4 appears 3 times: 1×4, 2×2, 4×1. Count 6, 15, 24 and 49.
Your answer
How to solve
Strategy Make a Systematic List — For each target number, list every way to write it as (first factor) x (second factor) with both factors from 1 to 9. Going through the small factors in order (1, 2, 3, ...) makes sure no pair is missed and none is double-counted.
1STEP 1

Count the facts for 6

6 comes from 1×6, 2×3 and their swaps — 4 times.

1{×}6, 2{×}3, 3{×}2, 6{×}1 → 4
2STEP 2

Count the facts for 15

15 has only 3×5 and 5×3 — twice.

3{×}5, 5{×}3 → 2
3STEP 3

Count the facts for 24

24 gives 3×8, 4×6 and swaps — 4 times; 2×12 is off the table.

3{×}8, 8{×}3, 4{×}6, 6{×}4 → 4
4STEP 4

Count the facts for 49

49 is only 7×7, and equal factors give one.

7{×}7 → 1
Answer
6 four times, 15 twice, 24 four times, 49 once
Each count matches the number of ordered factor pairs within 1-9: numbers with two factor pairs of different numbers give 4, a single mixed pair gives 2, and a number that is only a square of one factor gives 1. None of the listed pairs uses a factor above 9, so no count is inflated.
Takeaway

Counting how often a number shows up is just finding all its factor pairs that fit in 1-9 and remembering both orders count!

  • Count the facts for 6
  • Count the facts for 15
  • Count the facts for 24
  • Count the facts for 49