Skip over navigation
Really Mr. Bond
Age 14 to 16
Challenge Level 
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?
You may also like
DOTS Division
Take any pair of two digit numbers x=ab and y=cd where, without loss of generality, ab > cd . Form two 4 digit numbers r=abcd and s=cdab and calculate: {r^2 - s^2} /{x^2 - y^2}.
Novemberish
a) A four digit number (in base 10) aabb is a perfect square. Discuss ways of systematically finding this number. (b) Prove that 11^{10}-1 is divisible by 100.
