Currently my monthly wage is £840.
next month i will recieve a 7% rise.

fill this sum in:

£840 x = £

840 × 107/100% = $898.80 :)

In order to find out what our next monthly wage will be we have to multiply 
100% + 0.07% x £840 

Now you cant really multiply percents.. So we have to turn the percents into decimals. 
100% = 1.00
0.07% = 0.07 

Now add those two decimals together. 
1.00 + 0.07 = 1.07 

So our answer would look like this. 

£840 x _1.07_  = _898.8_

Good Luck! :)