courses › Mental Arithmetic

Division as a missing factor, then bigger exact divisions.

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

Learn first (about 3 minutes)

Opens at level 6.

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Builds on: Times tables (not open yet)

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.

• Division facts par 3 s not tried yet

  worked example

  16 ÷ 8

  Answer: 2

  1. Read it as a missing factor: 8 × ? = 16. Since 8 × 2 = 16, the answer is 2.

• Divide with zeros par 7 s not tried yet

  worked example

  120 ÷ 60

  Answer: 2

  1. Cancel a zero from both numbers: 120 ÷ 60 = 12 ÷ 6.
  2. 12 ÷ 6 = 2, because 6 × 2 = 12.

• Split the dividend par 7 s not tried yet

  worked example

  225 ÷ 15

  Answer: 15

  1. Split 225 into 150 + 75.
  2. 150 ÷ 15 = 10 and 75 ÷ 15 = 5, so the answer is 15.

• ÷ 0.5 and ÷ 0.25 par 7 s not tried yet

  worked example

  35 ÷ 0.25

  Answer: 140

  1. Dividing by 0.25 asks how many quarters fit. Each whole holds 4 quarters, so 35 × 4 = 140.

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

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