**Today’s Challenge**

Here’s a selection of mental arithmetic questions. Can you get all seven correct?

- (10 + 10) – (15 – 3) = ?
- What is the sum of 0.83 and 0.89?
- What is 1 × 9?
- If Ben earns £10 every half-hour, how much will he earn in 40 hours?
- If you burn 100 calories by climbing 100 stairs, how many calories do you burn when climbing 50 stairs?
- What is 5456 – 4372?
- Twice my age plus 4 more is 72. How old am I?

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**The 7puzzle Challenge**

The playing board of **the 7puzzle game** is a 7-by-7 grid containing 49 different numbers, ranging from **2 **up to **84**.

The 2nd & 5th rows of the playing board contain the following fourteen numbers:

6 7 8 16 17 21 28 48 50 55 63 64 81 84

What is the product of the two prime numbers?

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**Answers**

. . . can be found when **clicking this**.