Englishfor English speakers
arithmetical
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adjective
(= arithmetic)
relating to or involving arithmetic
arithmetical computations
instruction
Noun
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An instruction is a command or a step that helps you achieve a goal.
Before he died, he gave the hospital instructions about how to deal with his body.
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The instructions that come with a new machine, computer, or product tell you how to use the product.
I couldn't figure out how to set the temperature in the fridge, so I read the instructions.