What is 0.51 as a fraction?

0.51 as a fraction is 51/100. The digits go over 100, and 51 and 100 share no common factor, so it is already in lowest terms.

What is 0.51 as a percentage?

0.51 is 51%. Multiplying a decimal by 100 moves the point two places to the right.

How many millimetres is 0.51 of an inch?

0.51 inches is 12.954 mm, using the exact definition 1 inch = 25.4 mm.

0.51 as a fraction

Fraction51/100lowest terms

Decimal0.51

Percent51%

How to get there

0.51 has 2 digits after the point, so it is that many hundredths: write the digits over 100 — 51/100.
51 and 100 share no factor but 1, so 51/100 is already in lowest terms.

51 of 100 squares — 0.51 of the whole, which is also 51%.

As a measurement

Read as inches, 0.51″ is 12.954 mm exactly. The nearest marks on a rule:

Rule	Nearest mark	Inches	mm	Difference
16ths	1/2″	0.5	12.7	−0.254 mm
32ths	1/2″	0.5	12.7	−0.254 mm
64ths	33/64″	0.515625	13.0969	+0.1429 mm

Common questions

What is 0.51 as a fraction?: 0.51 as a fraction is 51/100. The digits go over 100, and 51 and 100 share no common factor, so it is already in lowest terms.
What is 0.51 as a percentage?: 0.51 is 51%. Multiplying a decimal by 100 moves the point two places to the right.
How many millimetres is 0.51 of an inch?: 0.51 inches is 12.954 mm, using the exact definition 1 inch = 25.4 mm.

The same number, other ways

51/100Everything about the fraction: equivalents, the bar model, the number line.51%The same value as a percentage, with its own derivation.Decimal → fraction chartThe whole lookup table, printable.Nearest fractionMatch 0.51″ against any rule, with the exact error.

Where this comes from. Exact rational arithmetic on the values shown — fractions are pairs of integers until display, and inch–metric conversion uses 25.4 mm to the inch, exact by definition since 1959. See the full methodology.