Over the years skills of the decision even of the simplest mathematical examples can be effaced from the memory if you got used to consider only on the calculator or owing to the activity almost do not face calculations.
Instruction
1. If you need to calculate the difference between, for example, amounts of a rent last and current month, and there is no calculator near at hand then not to do without subtraction by "column". The sums which should be paid for utilities, quite impressive today.
2. Write down the number having bigger value, and it is strict under it – the having smaller value. Draw under them a line. Begin subtraction with units (the last figure in each number), then – subtract the friend from the friend dozens (the second figure since the end), hundreds and thousands. Under horizontal line the required number gradually will appear. If initial numbers look approximately so: 2578 and 1466, that subtraction will come to you easily.
3. If such numbers as, for example, 2322 and 2278, then you can be at a loss with performance of arithmetic action got to you if you did not practice in it long ago. Again write down bigger number over smaller and draw a line. As at actions with positive numbers it is (more than 0), you will not be able from 2 to subtract 8, you should resort to small cunning after all to learn the difference of numbers.
4. "Occupy" the following category (designating dozens) one dozen (that is 10). Put over figure at which "loan", a point is made not to forget that in initial number there were already not two, but one dozen. From 12 subtract 8. Now you pass to dozens. But as to subtract from the remained unit 7 at you too it will not turn out, you should "occupy" ten the following category (designating hundreds) again. Do not forget to put the end over figure. From 11 subtract 7.
5. Learn number necessary for you and set skills of subtraction by a column, having decided some more examples, different in level of complexity.