Our new topic is Indices.An Indice or Index is a bit of mathematics speak for writing down how many times you want to multiply something together:
103 = 10 x 10 x 10 = 1000
We say in words 'Ten to the power of three' and this means we multiply three 10s together. The '3' is the Indice or Index or Power which tells us how many 10's we want to multiply. The '10' is the 'Base' which is 'raised' to the Indice.
It means we can work with very large and very small numbers in a simple and easy way.
For instance if we wanted to work out a problem that involved the number 'one million billion' we could write
1000000000000000 down and work with that, or we could simply write
1015There are some excellent short cuts that can be taken with Indices. If we had to multiply two numbers like 102 and 103 we notice this:
102 x 103 = (10 x 10) x (10 x 10 x 10) = 10 x 10 x 10 x 10 x 10 = 105
And we realise that we can use a more general rule when multiplying anything with the same 'base':
am x an = am+n
Which means that we can simply add up the indices to find the answer:
95 x 93 = 95 + 3 = 98
How easy is that!
More good shortcuts with Indices next week.
