Hi everyone!!'m approaching the subject of mental calculation and I would like to take very good care of the bases. So I’m practicing the left to right method of addition and I have found a little problem doing addition with 4+ figures.
For what I know with LtoR you go at every step you look forward one step to take care of the carrying. Let’s say we have 57 + 64, while you are doing the step 5+6 you look forward and see 4+7 is greater than 9 so you add the carrying while you are stating the result.
Now, when you have bigger numbers you have just to repeat this “looking forward” for the number of figures. Let’s say 1234+5678, while I’m doing 1+5 I look forward to 2+6, while I’m doing 2+6 I look forward to 7+3 etc.
So the routine should be adding the first number, look forward to see if there’s any carrying, stating the first result number, adding the second number, look forward to see if there’s any carrying, stating the second result number etc.
However let’ say I have 3444+1557. If I do my usual routine I would state the first number as a 4 because looking forward till the second figure would suggest me that I have no carrying. In reality the result is clearly wrong because the last carrying (7+4) will affect the result.
How do people solve this problem for 4+ figures numbers in order not to risk to make mistakes in their performances?