# Monthly Archives: January 2021

## DAY/DYDD/PÄIVÄ/NAP 20

The Main Challenge Consider all whole numbers from 1 to 60, then delete the following: all prime numbers, … and any number that differs by 1 from a prime, all square numbers, … and any number that differs by 1 from a square, … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 19

The Main Challenge Only one of the following 3-digit numbers is divisible by 3. Which one? 136 139 245 248 353 357 466 469 572 578 680 [Note: If you don’t know the trick on how to work this out, please … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 18

The Main Challenge All nine numbers from 21 to 29 inclusive must be allocated to a letter below so that each allocated number satisfies the condition given on the line: (a) even number, (b) factor of 144, (c) power of 3, (d) prime … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 17

The Main Challenge Find the answer to this large number trail which involves fourteen arithmetical steps and includes fraction and percentage calculations. Start with the number 11, then: double it 50% of this +50 subtract thirty-five ÷2 +37 3/5 of … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 16

The Main Challenge What is the sum of the 50 integers (or whole numbers) from 1 through to 50 inclusive? 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 … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 15

The Main Challenge Your task is to multiply two numbers together and then subtract a third number to achieve the target answer of 7. The three numbers used in each calculation must all be unique digits from 1-9. For example, … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 14

The Main Challenge Insert the 12 numbers 1 1 2 2 2 3 5 5 6 7 8 and 8 so that all three lines work out arithmetically: ◯ + ◯ = 6 = … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 13

The Main Challenge Starting from 2, list the first seven even numbers that are NOT multiples of 3, 5 or 7. What is the 7th number in your list? The 7puzzle Challenge The playing board of the 7puzzle game is a 7-by-7 grid containing 49 … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 12

The Main Challenge Add together the 7th prime number, the 7th square number, the 7th 2-digit number and the 7th whole number that contains a 7. What is your answer? The 7puzzle Challenge The playing board of the 7puzzle game is a 7-by-7 … Continue reading

## DAY/DYDD/PÄIVÄ/NAP 11

The Main Challenge Today’s task is to arrive at the target number of 7 by using the four numbers 7, 7, 7 and 7 once each. All four arithmetic operations + – × ÷ are available. Can you do it? The 7puzzle … Continue reading