Here's the puzzle we've been working on today...
so, it's a friend's birthday. She is 10years old. If she had a cake for every birthday so far, with the number of candles matching her age, how many candles will she have blown out in her lifetime?
It's like this....when she was, say, 4 years old, she will have blown out 1 candle for age 1, 2 when she was2...3 when she was 3 and 4 now she is 4. So that's 1+2+3+4=10. When she was 4 there had been 10 candles. Can you work out how many for age 10?
Ask your careers their age...how many candles for them? Is there a fast way to add the numbers?
Here we are working on this today.