You may also like

problem icon

Number Detective

Follow the clues to find the mystery number.

problem icon

Six Is the Sum

What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?

problem icon

(w)holy Numbers

A church hymn book contains 700 hymns. The numbers of the hymns are displayed by combining special small single-digit boards. What is the minimum number of small boards that is needed?

One Million to Seven

Stage: 2 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Many of you have had an excellent stab at this problem - it requires a lot of perseverance - and you have come up with several ways, all of which take four steps. Matthew from Gayhurst School suggests:

$1 000 000 \times 7 = 7 000 000$
$7 000 000 + 777 777 = 7 777 777$
$7 777 777\div 7 777 777 = 1$
$1 \times 7 = 7$

Tom, who goes to The Oratory Preparatory School found a different way which is equally as quick:

$1000000\times77=77000000$
$+777777=77777777$
$\div 77777777=1$
$\times7 =7$

Yet another way was discovered by Robert from U-Hill Secondary and pupils from the Sutton Masterclass:

$1 000 000 \times 7 = 7 000 000$
$7 000 000 + 777 777 = 7 777 777$
$7 777 777 - 7 777 777 = 0$
$0 + 7 = 7$

Pupils from Moorfield Junior School told us about a fourth way:

$1,000,000\times 7 =7,000,000$
$7,000,000 - 7,777,777 = -777,777$
$-777,777 + 777,777 = 0$
$0 + 7 =7$

Theo, Matthew, Seth and Jessie from Christ Church Primary School went about it in this way:

$1 000 000\div 77 777 777 = 0.0128571$
$0.0128571\div 77 777 777 = 0$
$0 + 7 = 7$

This is interesting. I'm particularly intrigued by the second line. I wonder why the calculator display gives zero?

Fantastic - and to think it looked so difficult!