21/32 as a decimal
21/32 = 0.65625 inches = 16.6687 mm.
0.65625
21/32 of an inch
Millimetres
16.6687 mm
Centimetres
1.66687 cm
Percent
65.625%
Decimal
terminates
32 goes into 21 0 times with 21 left over, so write 0 and a decimal point. Then bring down a zero and divide again, one digit at a time.
| Step | Divide | Digit | Subtract | Remainder |
|---|---|---|---|---|
| 1 | 210 ÷ 32 | 6 | 210 − 192 | 18 |
| 2 | 180 ÷ 32 | 5 | 180 − 160 | 20 |
| 3 | 200 ÷ 32 | 6 | 200 − 192 | 8 |
| 4 | 80 ÷ 32 | 2 | 80 − 64 | 16 |
| 5 | 160 ÷ 32 | 5 | 160 − 160 | 0 |
Remainder 0: nothing is left to divide, so the division stops and 21/32 = 0.65625 exactly.
Where 21/32 falls at each precision, and whether the mark is the value exactly
| Rule | Nearest mark | Exact? |
|---|---|---|
| 1/16 | 11/16 | nearest |
| 1/32 | 21/32 | exact |
| 1/64 | 21/32 | exact |
21/32 = 42/64
All the same mark. 21/32 is the form in lowest terms, which is how a rule labels it and how a cut list should read.
Mixed numbers with 21/32
A whole number of inches plus 21/32: the whole number goes in front of the decimal point and 21/32 supplies the digits after it
| Mixed | Inches | mm |
|---|---|---|
| 1 21/32 | 1.65625 | 42.0687 |
| 2 21/32 | 2.65625 | 67.4688 |
| 3 21/32 | 3.65625 | 92.8687 |
| 4 21/32 | 4.65625 | 118.2687 |
| 5 21/32 | 5.65625 | 143.6687 |
| 6 21/32 | 6.65625 | 169.0687 |
| 7 21/32 | 7.65625 | 194.4688 |
| 8 21/32 | 8.65625 | 219.8687 |
| 9 21/32 | 9.65625 | 245.2687 |
| 10 21/32 | 10.65625 | 270.6687 |
| 11 21/32 | 11.65625 | 296.0687 |
| 12 21/32 | 12.65625 | 321.4688 |
Converting 21/32 to a decimal
A fraction is a division. 21/32 = 21 ÷ 32 = 0.65625. The decimal terminates because 32 factors into 2 × 2 × 2 × 2 × 2 — only 2s and 5s, the factors of ten. Any fraction whose denominator is built from those has an exact decimal.
In metric that is 16.6687 millimetres (1.66687 cm), since one inch is exactly 25.4 mm. As a percentage of an inch it is 65.625%.
21/32 is a real mark on a rule: it is the 21/32 mark on a 1/32 rule, and the same mark is written 42/64 at finer precisions.
Going the other way
To turn 0.65625 back into a fraction, pick the precision you are working to and multiply. At 1/16: 0.65625 × 16 = 10.5, giving 11/16 after rounding to the nearest mark. At 1/32: 0.65625 × 32 = 21, giving 21/32 exactly. At 1/64: 0.65625 × 64 = 42, giving 21/32 exactly.
What is 21/32 as a decimal?
21/32 as a decimal is 0.65625. Divide the numerator by the denominator: 21 ÷ 32 = 0.65625. The division comes out exactly, with no remainder left over.
What is 2 21/32 as a decimal?
2 21/32 as a decimal is 2.65625. The whole number stays in front of the decimal point and 21/32 supplies the digits after it, so 2 21/32 = 2 + 0.65625. In millimetres that is 67.4688 mm. This page's mixed-numbers table runs from 1 21/32 to 12 21/32.
What is 21/32 as a percent?
21/32 as a percent is 65.625%. Multiply the decimal by 100: 0.65625 × 100 = 65.625%.
What is 0.65625 as a fraction?
0.65625 as a fraction is 21/32, in lowest terms. It can also be written 42/64, which are the same value expressed over a larger denominator.
How many millimetres is 21/32 of an inch?
21/32 of an inch is 16.6687 mm, or 1.66687 cm. An inch has been defined as exactly 25.4 mm since 1959, so this conversion is a definition rather than a measurement — the millimetre value is exact too.
Where is 21/32 on a tape measure?
21/32 is a real mark on a rule: it is the 21/32 mark on a 1/32 rule, and the same mark is written 42/64 at finer precisions.