Take a look at 47 + 38. No pencil, no paper, no column method. Could you work it out in your head?

There's more than one way to do it. Today we'll look at three of them, and by the end of the lesson you'll be able to pick the one that best suits the numbers in front of you.

Watch four worked examples on the number line. Same answer every time, but the route across the line is different. Notice how each strategy uses the numbers in a slightly different way.

Example 1: 47 + 38 by partitioning

Split the 38 into 30 + 8. Jump +30 first to land on 77, then jump +8 to land on 85.

Example 2: 47 + 38 by compensating

40 is friendlier than 38. Jump +40 to land on 87, then take back the extra 2 to land on 85.

Example 3: 47 + 38 by bridging through fifty

50 is the friendliest landing place near 47. Jump +3 to land on 50, then jump +35 in one go to land on 85.

Example 4: 235 + 198 by compensating

198 is almost 200. Jump +200 to land on 435, then take back the extra 2 to land on 433. Compensating shines when one number is just below a round hundred.

Today's problem: 38 + 27. Three pupils in turn will come to the board — one for each strategy — and drag the jump arcs onto the number line to reach the answer. The strategy-hint label confirms which one they used.