Place value

Write down a three-digit number Change the order of the digits to get a different number Find the difference between the two three digit numbers Follow the rest of the instructions then try to explain why this works.

Can you substitute numbers for the letters in these sums?

Replace each letter with a digit to make this addition correct.

Visitors to Earth from the distant planet of Zub-Zorna were amazed when they found out that when the digits in this multiplication were reversed, the answer was the same! Find a way to explain why this works.

Replace the letters with numbers to make the addition work out correctly. R E A D + T H I S = P A G E

I am less than 25. My ones digit is twice my tens digit. My digits add up to an even number.

Find b where 3723(base 10) = 123(base b).

Can you produce convincing arguments that a selection of statements about numbers are true?

When the number x 1 x x x is multiplied by 417 this gives the answer 9 x x x 0 5 7. Find the missing digits, each of which is represented by an "x" .

115^2 = (110 x 120) + 25, that is 13225 895^2 = (890 x 900) + 25, that is 801025 Can you explain what is happening and generalise?