Add 9: Addition Facts

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Add 9 has a famous shortcut: it is one less than adding ten, so it comes from the easiest family there is.

Counting on from 9

For the other number from 2 to 9, the ones digit of the answer is one less than that number: 9 + 6 = 15 ends in 5, and 9 + 8 = 17 ends in 7.

Add 10, then take away 1. For 9 + 6, 10 + 6 = 16, and one less is 15.

The shortcut works for all of them, but 9 + 9 = 18 should also be known as a double. Practice 'add 10, take 1' until it is fast.

Swapping the numbers gives the same answer, so each fact below is learned once and used twice.

Untimed by default. A missed fact shows its answer and comes back later in the round.

One US Letter page, clear in black and white.

10 questions, no timer. At the end you see the score, the facts to practice and a sheet you can print.

Nine is ten minus one, so adding 9 is the same as adding 10 and stepping back one. It works for any number.

The answer is always 1 less than 10 plus the other number. If 9 + 7 gave 17, that is 10 + 7 with no step back, so it is wrong; 16 is right.