Drills

Maths drill

Grid Multiplication

Split the numbers, multiply the easy bits, add them up.

How it works

  • 1Split each number into tens and units: 42 = 40 + 2, 86 = 80 + 6.
  • 2Draw a grid on paper — one number across the top, the other down the side.
  • 3Multiply each pair. Cross off the zeros to make it easy: 40 × 80 → 4 × 8 = 32 → put the two zeros back → 3200.
  • 4Add all four boxes. Stack them one under the other and add column by column.
  • 5Decimals? Ignore the points, multiply, then move the point back at the end: 4.2 × 8.6 → 42 × 86 = 3612 → 36.12.

Worked example

42 × 86
40×80 = 3200 40×6 = 240
2×80 = 160 2×6 = 12
3200 + 240 + 160 + 12 = 3612