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Codice & Numeri
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Arithmetic lab / game

Four or five numbers, one hundred targets

Choose 4 or 5 numbers, edit them or draw them randomly. Find the group that makes the most different results from 1 to 100. Tap a green number to see a formula and every calculation step.

Arithmetic Rules and strategies ITENFRES

The 4 numbers

Whole numbers from 1 to 99; repeated values are allowed. Use all 4 numbers exactly once each.

Compare all groups of 4 numbers

With 4 numbers, the complete precomputed search goes up to 20; manual values still allow 1 to 99. If several groups tie, one is shown. Session records are separate for the two modes.

Rules and calculation method
  • Choose 4 or 5 numbers. Use all entered numbers exactly once each, in any order. Two equal values still occupy two separate positions and must both be used.
  • Only addition, subtraction, multiplication, division and parentheses are allowed. Joining numbers, powers, roots and factorials are not allowed.
  • Intermediate results may be fractions, zero or negative numbers. Division by zero is never allowed.
  • Only whole-number final results from 1 to 100 count. Different formulas giving the same result earn just one point.
  • Records last only while this game is open and are separate for 4 and 5 numbers: no account is needed and nothing is saved on your device.

The lab explores every partition of the numbers into groups, combines results with the four operations and keeps exact fractions. Grey means impossible under these rules, not merely a solution that has not yet been searched for.