At the 7puzzle company, we produce regular number puzzles for our many followers from 117 different countries (at the last count). Our aim is to help improve the basic knowledge and confidence of number & arithmetic in a fun way for people all over the world.
Enjoy your visit and spread the message about the fabulous number puzzles at 7puzzleblog.com. Try our latest re-cycled challenges, #82 & #83, in which your mental arithmetic skills will be fully tested. There are over 1,000 number challenges to try at this website.
You can also follow me and my tweets at @7puzzle.
Paul Godding: Owner, the 7puzzle company
Short and sweet – what is the sum of all whole numbers from 10-20 inclusive?
By using each of the numbers 0.8, 0.9, 1.5 and 5 once each, and with the four arithmetical operations available to use, can you arrive at the target answer of 7?
Do the following calculations in your head and improve your mental arithmetic. For the speedy ones out there, you have 20 seconds to get the correct answer to this 15-step question.
Start with the number 20, then:
+1 ÷3 x5 -7 +2 ÷6 +4 -1 x3 ÷4 +4 -5 x4 -5 x4 = ?
What is your final answer?
Each of the nine letters, A-I, in the two sections below contain a subtraction calculation:
C:24-13 G:14-6 D:20-10 E:15-7 I:14-9 F:18-11 B:9-2 A:17-5 H:25-12
I:16-3 A:15-1 H:20-8 C:19-9 G:12-4 E:11-5 F:21-6 D:14-7 B:27-18
Which is the only letter that has the same numerical value in both sections?
From the numbers 1-30, find the only one that remains when you eliminate the following:
- numbers containing a 1
- prime numbers
- numbers in the 20′s
- factors of 72
When playing the possible game, you need to use a bit of creative numerical thinking, exactly like this:
Using 5 5 5 once each, with + – × ÷ available, which SEVEN target numbers from 1-30 are mathematically possible to achieve?
The two sections below both contain eight letters, A to H, each with a calculation:
E:8×3 B:30÷2 H:15+3 A:6×6 G:36÷3 C:40-20 F:18+12 D:32-8
G:10+6 F:6×5 C:9×4 E:40÷2 H:30-18 A:15+9 D:30-12 B:120÷4
Which is the only letter to have the SAME answer in BOTH sections?
It is possible to use seven 4′s (4 4 4 4 4 4 4) once each, with the four operations + – x ÷, to make all the target numbers from 1-9.
For instance, to arrive at the number 1, you could do:
4 – (4÷4) – (4÷4) – (4÷4) = 1
Your task is to make each of the other target numbers 2-9 using seven 4′s. Can you make them all?
P.S. As an added bonus question for the real puzzle enthusiast, what is the LOWEST target number it is NOT possible to make using the seven 4′s?
Try the following calculations in your head to help improve your mental arithmetic. For the speedy number gymnasts, you have 10 seconds to get the correct answer to this 10-step question.
Start with the number 13, then:
-2 +5 ÷2 x5 -4 ÷9 +1 x5 -1 ÷4 = ?