What is 0.9 as a fraction?

0.9 as a fraction is 9/10. The digits go over 10, and 9 and 10 share no common factor, so it is already in lowest terms.

What is 0.9 as a percentage?

0.9 is 90%. Multiplying a decimal by 100 moves the point two places to the right.

How many millimetres is 0.9 of an inch?

0.9 inches is 22.86 mm, using the exact definition 1 inch = 25.4 mm.

0.9 as a fraction

Fraction9/10lowest terms

Decimal0.9

Percent90%

How to get there

0.9 has 1 digit after the point, so it is that many tenths: write the digits over 10 — 9/10.
9 and 10 share no factor but 1, so 9/10 is already in lowest terms.

90 of 100 squares — 0.9 of the whole, which is also 90%.

As a measurement

Read as inches, 0.9″ is 22.86 mm exactly. The nearest marks on a rule:

Rule	Nearest mark	Inches	mm	Difference
16ths	7/8″	0.875	22.225	−0.635 mm
32ths	29/32″	0.90625	23.0188	+0.1588 mm
64ths	29/32″	0.90625	23.0188	+0.1588 mm

Common questions

What is 0.9 as a fraction?: 0.9 as a fraction is 9/10. The digits go over 10, and 9 and 10 share no common factor, so it is already in lowest terms.
What is 0.9 as a percentage?: 0.9 is 90%. Multiplying a decimal by 100 moves the point two places to the right.
How many millimetres is 0.9 of an inch?: 0.9 inches is 22.86 mm, using the exact definition 1 inch = 25.4 mm.

The same number, other ways

9/10Everything about the fraction: equivalents, the bar model, the number line.90%The same value as a percentage, with its own derivation.Decimal → fraction chartThe whole lookup table, printable.Nearest fractionMatch 0.9″ 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.