courses › Mental Arithmetic

Every fact from 1 × 1 to 12 × 12, recalled rather than counted.

Best in your head · no pen, no calculator why?

Learn first (about 3 minutes)

Opens at level 3.

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Builds on: Small facts

skills · practice stats

From rounds of this course only: box, review and trial answers are left out. Once a skill has 40 tries, it compares your first 20 tries with your last 20.

• × 2, 4, 5, 8, 10 par 3 s not tried yet

  worked example

  11 × 4

  Answer: 44

  1. × 4 is two doublings: 11 → 22 → 44.

• × 3, 6, 9 par 3 s not tried yet

  worked example

  9 × 1

  Answer: 9

  1. × 9 is × 10 minus one copy: 10 − 1 = 9.

• × 7, 11, 12 and squares par 3 s not tried yet

  worked example

  11 × 1

  Answer: 11

  1. × 11 is × 10 plus one copy: 10 + 1 = 11.

• Mixed facts par 3 s not tried yet

  worked example

  12 × 2

  Answer: 24

  1. × 2 is doubling: 12 + 12 = 24.

rest ladder

Win 3 of your last 4 rounds and the course rests. A win is 90% right, within 2× the round's par. Pass the review when it comes back and the next rest is longer.

1. 1 day
2. 3 days
3. 7 days
4. 14 days
5. 30 days
6. 60 days
7. mastered · every 90 days

your rounds

No rounds yet.