T he Main Challenge
Here’s seven more mental arithmetic questions to try. Can you get all seven correct?
- (11 – 5) – (4 + 1) = ?
- What is 10 more than –4?
- 47 × 4 = ?
- 0.32 ÷ 4 = ?
- 3/4 × 2/3 = ?
- Which one is bigger: 2 cubed or 3 squared?
- You wish to buy two £30 items. Which offer would give you the best deal: (A) 15% off both items, (B) 2nd item is 40% off, (C) get 1/3 off the 2nd item, (D) 25% off 1st item, 10% off 2nd item.
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 1st & 2nd rows contain the following fourteen numbers:
2 8 9 14 15 17 22 28 40 48 55 63 64 72
From the list, find TWO numbers that have a sum of 111.
The Lagrange Challenge
Lagrange’s Four-Square Theorem states that every positive integer can be made by adding up to four square numbers.
For example, 7 can be made by 2²+1²+1²+1² (or 4+1+1+1).
There are SEVEN ways of making 108 when using Lagrange’s Theorem. Can you find them all?
The Mathematically Possible Challenge
Using 1, 4 and 9 once each, with + – × ÷ available, which THREE numbers is it possible to make from the list below?
6 12 18 24 30 36 42 48 54 60
#6TimesTable
The Target Challenge
Can you arrive at 108 by inserting 2, 3, 5 and 11 into the gaps on both lines?
- ◯²×◯²+◯–◯ = 108
- ◯×◯²+◯²+◯ = 108
Answers can be found here.
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