What is 0.42 as a fraction?

0.42 as a fraction is 21/50. Write the digits over 100 to get 42/100, then divide top and bottom by 2.

What is 0.42 as a percentage?

0.42 is 42%. Multiplying a decimal by 100 moves the point two places to the right.

How many millimetres is 0.42 of an inch?

0.42 inches is 10.668 mm, using the exact definition 1 inch = 25.4 mm.

0.42 as a fraction

Fraction21/50lowest terms

Decimal0.42

Percent42%

How to get there

0.42 has 2 digits after the point, so it is that many hundredths: write the digits over 100 — 42/100.
42 and 100 share a greatest common divisor of 2. Divide both by it: 21/50.

42 of 100 squares — 0.42 of the whole, which is also 42%.

As a measurement

Read as inches, 0.42″ is 10.668 mm exactly. The nearest marks on a rule:

Rule	Nearest mark	Inches	mm	Difference
16ths	7/16″	0.4375	11.1125	+0.4445 mm
32ths	13/32″	0.40625	10.3188	−0.3493 mm
64ths	27/64″	0.421875	10.7156	+0.0476 mm

Common questions

What is 0.42 as a fraction?: 0.42 as a fraction is 21/50. Write the digits over 100 to get 42/100, then divide top and bottom by 2.
What is 0.42 as a percentage?: 0.42 is 42%. Multiplying a decimal by 100 moves the point two places to the right.
How many millimetres is 0.42 of an inch?: 0.42 inches is 10.668 mm, using the exact definition 1 inch = 25.4 mm.

The same number, other ways

21/50Everything about the fraction: equivalents, the bar model, the number line.42%The same value as a percentage, with its own derivation.Decimal → fraction chartThe whole lookup table, printable.Nearest fractionMatch 0.42″ 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.