Operation span

Judge a sum, remember the letter that follows it, and repeat. When the sums run out, type the letters back in order.

Each sum has a time limit. It is generous, but it stops you rehearsing.

Judge the sum, hold the letter.

Decide whether each sum on screen is right or wrong. After each one you will see a letter to remember. When the sums run out, type all the letters in the order you saw them.

How to play

A sum appears, like 7 × 4 = 26. Decide whether it is right or wrong.

As soon as you answer, the sum disappears and a letter takes its place. Remember it. Then the next sum appears.

When the sums run out, type every letter you saw, in order.

Each sum has a time limit. It is generous, because this is not an arithmetic speed test. It exists so you cannot sit on the sum and rehearse the letters, which is what the sums are there to prevent.

Letters never repeat within a round, and there are no vowels, so the run cannot be held as a word.

Your recall and your sums are reported separately. Ignoring the sums to protect the letters shows up in the score rather than being averaged away.

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