4/5 as a decimal
4/5 = 0.8 inches = 20.32 mm.
0.8
4/5 of an inch
Millimetres
20.32 mm
Centimetres
2.032 cm
Percent
80%
Decimal
terminates
5 goes into 4 0 times with 4 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 | 40 ÷ 5 | 8 | 40 − 40 | 0 |
Remainder 0: nothing is left to divide, so the division stops and 4/5 = 0.8 exactly.
Where 4/5 falls at each precision, and whether the mark is the value exactly
| Rule | Nearest mark | Exact? |
|---|---|---|
| 1/16 | 13/16 | nearest |
| 1/32 | 13/16 | nearest |
| 1/64 | 51/64 | nearest |
Mixed numbers with 4/5
A whole number of inches plus 4/5: the whole number goes in front of the decimal point and 4/5 supplies the digits after it
| Mixed | Inches | mm |
|---|---|---|
| 1 4/5 | 1.8 | 45.72 |
| 2 4/5 | 2.8 | 71.12 |
| 3 4/5 | 3.8 | 96.52 |
| 4 4/5 | 4.8 | 121.92 |
| 5 4/5 | 5.8 | 147.32 |
| 6 4/5 | 6.8 | 172.72 |
| 7 4/5 | 7.8 | 198.12 |
| 8 4/5 | 8.8 | 223.52 |
| 9 4/5 | 9.8 | 248.92 |
| 10 4/5 | 10.8 | 274.32 |
| 11 4/5 | 11.8 | 299.72 |
| 12 4/5 | 12.8 | 325.12 |
Converting 4/5 to a decimal
A fraction is a division. 4/5 = 4 ÷ 5 = 0.8. The decimal terminates because 5 factors into 5 — only 2s and 5s, the factors of ten. Any fraction whose denominator is built from those has an exact decimal.
In metric that is 20.32 millimetres (2.032 cm), since one inch is exactly 25.4 mm. As a percentage of an inch it is 80%.
4/5 is not a mark on any imperial rule — the denominators on a rule are all powers of two, and 5 is not one. The nearest marks are 13/16 on a 1/16 rule, 13/16 on a 1/32 rule, 51/64 on a 1/64 rule, none of them exact.
Going the other way
To turn 0.8 back into a fraction, pick the precision you are working to and multiply. At 1/16: 0.8 × 16 = 12.8, giving 13/16 after rounding to the nearest mark. At 1/32: 0.8 × 32 = 25.6, giving 13/16 after rounding to the nearest mark. At 1/64: 0.8 × 64 = 51.2, giving 51/64 after rounding to the nearest mark.
What is 4/5 as a decimal?
4/5 as a decimal is 0.8. Divide the numerator by the denominator: 4 ÷ 5 = 0.8. The division comes out exactly, with no remainder left over.
What is 2 4/5 as a decimal?
2 4/5 as a decimal is 2.8. The whole number stays in front of the decimal point and 4/5 supplies the digits after it, so 2 4/5 = 2 + 0.8. In millimetres that is 71.12 mm. This page's mixed-numbers table runs from 1 4/5 to 12 4/5.
What is 4/5 as a percent?
4/5 as a percent is 80%. Multiply the decimal by 100: 0.8 × 100 = 80%.
What is 0.8 as a fraction?
0.8 as a fraction is 4/5, in lowest terms.
How many millimetres is 4/5 of an inch?
4/5 of an inch is 20.32 mm, or 2.032 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 4/5 on a tape measure?
4/5 is not a mark on any imperial rule — the denominators on a rule are all powers of two, and 5 is not one. The nearest marks are 13/16 on a 1/16 rule, 13/16 on a 1/32 rule, 51/64 on a 1/64 rule, none of them exact.