Keep the same whole
A denominator tells you how many equal parts make the whole. The numerator tells you how many parts you have.
Split each half into two equal pieces. One half becomes two quarters: 1/2 = 2/4. The whole and the shaded amount stay the same.
Scale both numbers
12 ÷ 3 = 4
2 × 4 = 8
2/3 = 8/12
To write 2/3 with denominator 12, find the scale factor: 12 ÷ 3 = 4.
Multiply both numbers by 4. The numerator becomes 8 and the denominator becomes 12, so 2/3 = 8/12.
Find the missing numerator
Complete 3/4 = ?/20. The whole stays the same, but each quarter is split into smaller equal pieces.
Find what multiplies 4 to make 20, then multiply 3 by that same number.
Try it
Which numerator completes 3/4 = ?/20?
- 15
- 19
Show the answer
15
4 × 5 = 20, so multiply the numerator by 5 too: 3 × 5 = 15. Thus 3/4 = 15/20.
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