Como dizer "regra de três" em inglês

Português: regra de três
Inglês: rule of three >> the method of finding the fourth term in a proportion when three terms are given. / a mathematical rule asserting that the value of one unknown quantity in a proportion is found by multiplying the denominator of each ratio by the numerator of the other. - Dictionary.com

Exemplos:

1. Use the rule of three to calculate the correction factor. Example: the original has a height of 120mm; the copy has a height of 126mm.
2. The expected full height is calculated by the rule of three from the current height. Proportional deviations are provided.

Leia também:

Cf. Como dizer "Ter vergonha" em inglês
Cf. Como dizer "conhecer" em inglês

Bons estudos.