$$\mathrm{\ }$$If there is seven thousand earthquakes in christchurch and 7/10ths are below a magnitude 6 then how many are above a magnitude 6
Great answer anon,
another way to do it is
$${\frac{{\mathtt{3}}}{{\mathtt{10}}}}{\mathtt{\,\times\,}}{\mathtt{7\,000}} = {\mathtt{2\,100}}$$
Can you see why ?
If anyone wants me to explain then please ask :)
$${\frac{{\mathtt{7}}}{{\mathtt{10}}}}{\mathtt{\,\times\,}}{\mathtt{7\,000}} = {\mathtt{4\,900}}$$, 1) This is the first step: to find 7/10ths of 7000
$${\mathtt{7\,000}}{\mathtt{\,-\,}}{\mathtt{4\,900}} = {\mathtt{2\,100}}$$ , 2) Then Subract
