The Rule
A 5-digit number will be displayed, for example 42211. Add all the digits down to a single number (1-9) and type it into the input box.
Example: 4+2+2+1+1 = 10, then 1+0 = 1
The Shortcut - Skip 9s!
Adding 9 to any number always gives you back that same number. So any 9, and any pair adding to 9, can be crossed out instantly.
2 + 9 = 11 = 2
7 + 9 = 16 = 7
5 + 9 = 14 = 5
Skip pairs: 1+8 2+7 3+6 4+5
Example: 6 3 9 4 3
6+3 gone 9 gone 4+3 = 7
Level Up - Memorize These!
Once you know these common pairs by heart, your speed jumps dramatically.
5+5 = 1 5+6 = 2 5+7 = 3
6+6 = 3 6+7 = 4 6+8 = 5
7+4 = 2 7+7 = 5 7+8 = 6
8+8 = 7 8+5 = 4 8+6 = 5
Tip: Think of these as instant answers, not math.
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