投 · Division & percent
Scroll of the Throw
Division is multiplication run backwards. See patterns, split numbers into friendly parts and turn fractions into money or percent.
Reverse Combo
Turn the question around: what times the divisor gives the number? Every table you know is a free division table.
56 ÷ 8
- → 8 × ? = 56
- → 8 × 7 = 56
Answer: 7
Practice: Try 63 ÷ 9, 84 ÷ 12 and 144 ÷ 16.
Halve and Halve
Dividing by 4 is halving twice. Dividing by 8 is halving three times.
68 ÷ 4
- → Half of 68 = 34
- → Half of 34 = 17
Answer: 17
Practice: Try 92 ÷ 4, 76 ÷ 4 and 120 ÷ 8.
Split the Load
Split a big number into two parts that each divide easily, then add the answers.
112 ÷ 7
- → 112 = 70 + 42
- → 70 ÷ 7 = 10, 42 ÷ 7 = 6
- → 10 + 6 = 16
Answer: 16
Practice: Try 91 ÷ 7, 132 ÷ 6 and 156 ÷ 12.
Balanced Blade
Halve or double both numbers — the answer stays the same, and the numbers get friendlier.
144 ÷ 18
- → Halve both: 72 ÷ 9
- → 72 ÷ 9 = 8
Answer: 8
Doubling works too: 90 ÷ 4,5 → 180 ÷ 9 = 20.
Practice: Try 126 ÷ 14 and 35 ÷ 2,5.
Coin Sense
For fractions below 1, think of 1 as a whole coin or 100 %. A fifth of 100 % is 20 %, so 1/5 = 0,2.
1/8
- → Think 100 ÷ 8 = 12,5
- → Make it 100 times smaller
- → 0,125
Answer: 0,125
1/2 = 0,5 · 1/4 = 0,25 · 1/5 = 0,2 (so 2/5 = 0,4, 3/5 = 0,6) · 1/10 = 0,1
Practice: Try 3/4, 3/5 and 3/8.
Shift the Point
Start from 10 %: move the decimal point one step left. Everything else is built from that.
20 % of 450
- → 10 % = 45
- → Double it: 20 % = 90
Answer: 90
5 % is half of 10 % (22,50). 15 % is 10 % + 5 % (67,50).
Practice: Try 10 %, 5 % and 30 % of 260.
Into the dojo
Practise with Throw ÷, Seal % and Flow ½ in Kung Fu Math or Junior from yellow belt.