What is 21/50 as a decimal?

21/50 is exactly 0.42 as a decimal.

How many millimetres is 21/50 of an inch?

21/50 of an inch is 10.668 mm, computed with the exact definition 1 inch = 25.4 mm.

21/50

Fraction21/50

Decimal0.42

Percent42%

21 of 50 equal parts filled .

Where the decimal comes from

21/50 equals 42/100 equals 0.42.

Multiply the top and bottom by 2 and the denominator becomes 100. A fraction over 100 is what a decimal is: 0.42 means 42 hundredths.

42 of 100 squares — 0.42 of the whole. The same squares read as a percentage: 42%, because percent means per hundred.

Every way to write it

Decimal: 0.42
Percent: 42%
Ratio: 21 : 50 (part to whole)
As inches: 21/50″ = 10.668 mm

Equivalent fractions

Multiply the top and bottom of 21/50 by the same number and the value does not change:

21/50 = 42/100 = 63/150 = 84/200 = 105/250 = 126/300 · more, or pick a denominator

On the number line

As a measurement

Read as inches, 21/50″ is 10.668 mm exactly. The nearest marks on the finer rules:

Rule	Nearest mark	Decimal 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

Need a different rule or a tolerance? Nearest fraction · Within tolerance

Common questions

What is 21/50 as a decimal?: 21/50 is exactly 0.42 as a decimal.
What is 21/50 as a percentage?: 21/50 is exactly 42%.
How many millimetres is 21/50 of an inch?: 21/50 of an inch is 10.668 mm, computed with the exact definition 1 inch = 25.4 mm.

0.42 as a fractionThe same number from the decimal's side, with the reduction shown.42% as a fractionThe same number as a percentage, with the work shown.Fraction–decimal chartThe everyday set, printable.Rule charts16ths, 32nds, 64ths, 128ths.The rulerSee 21/50 in its place.

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.