Video Transcript
Solve the following: 648.3628
minus 434.27.
So what we can see in this
question is that we’ve got two numbers: one with four decimal places, the other
with two. And that’s the values after the
decimal point. The calculation is set up
nicely in a column subtraction way with our decimal points aligned, which is
very, very important with this kind of question. Okay, but can we do anything
else to make it a bit easier for ourselves? So what we can do sometimes to
avoid any mistakes that might be made through errors in our method is add zeros
in any place values that are blank. So here we’ve got a zero in the
thousandths and ten thousandths for the bottom number.
And now what we do is carry out
subtraction as we would carry out any column subtraction, starting with the
right-hand side. So we’ve got eight minus zero,
which is eight, then two minus zero, which is two. Then, we move over to six minus
seven, being careful not to get stuck in the common mistake here, which would be
to do seven minus six, which gives us one. We have to do six minus seven,
which we can’t do. So we’re gonna borrow from the
place value to the left. So now, what we’ve done is
borrowed one to the tenths. So we’ve got two tenths
now.
And now what we’ve got in the
hundredths is sixteen hundredths instead of six. So we’ve got 16 minus seven,
which is nine. Then, we’ve got two minus two,
which is zero. And then, we put the decimal
point in exactly the same place that’s aligned. Then, we’ve got eight minus
four, which is four; four minus three, which is one; and then finally six minus
four. So therefore, we can say that
648.3628 minus 434.27 is 214.0928.