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A Square and A Cube

A number you can draw as a square

A tiler fixes floor tiles. His patch of floor is 7 tiles across. It has 7 rows. How many tiles is that?

A block, 7 tiles across and 7 tiles down.
Step 1 of 4
  1. A block, 7 tiles across and 7 tiles down.
  2. Top row: 7 tiles.
  3. Left column: 7 tiles.
  4. 7 × 7 = 49 tiles.

The patch has 49 tiles. Seven rows of 7 tiles make 7 × 7 = 49.

Rule: A square number is the tile count of a square. The same number of tiles go across as down.

We write 7 rows of 7 as 7². We say seven squared. The small raised 2 says two 7s are multiplied.

The first fifteen square numbers, each a real block of tiles
SideWrittenTiles
11²1
22²4
33²9
44²16
55²25
66²36
77²49
88²64
99²81
1010²100
1111²121
1212²144
1313²169
1414²196
1515²225

The side need not be a whole number. A square of side 2.5 has area 2.5 × 2.5 = 6.25. That is an area, not a square number. A square number is a whole number of tiles in a square. It needs a whole side.

Slide the side. Watch the tiles fill in.

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This track

  1. 0 Start here
  2. 1 A number you can draw as a square
  3. 2 Each new layer is the next odd number
  4. 3 A test that can only say no
  5. 4 Going back to the side you started from
  6. 5 Pairing the primes finds the side
  7. 6 Checkpoint: squares, the staircase and roots
  8. 7 When no whole number fits
  9. 8 A cube number counts real cubes
  10. 9 What cubes end in, and what they add up to
  11. 10 Grouping the primes in threes
  12. 11 Which count is the job asking for
  13. 12 Checkpoint: in between, cubes and cube roots
  14. 13 The big picture
  15. 14 Track quiz

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