A book has 730 pages. He read 574 pages yesterday and 145 pages today. How many pages are left?
We need to answer how many pages are left. To find that value, we take the total pages, subtract the completed pages, and we’re left with the remaining pages. The book has 730 pages. The reader read 574 pages yesterday and 145 pages today. If we want to find out the completed pages, we need to add how much he read yesterday and today.
We take yesterday, 574, and add today, 145. Starting in the units place, four plus five equals nine. In the tens place, seven plus four equals 11. Write down your one; carry your one. In the hundreds place, we add one plus five plus one, which equals seven. So far, the reader has read 719 pages, the completed pages, 719.
Now we know that 730 minus 719 tells us how many pages are remaining. We can stack these two values together vertically. When we subtract in our units place, we realize that we can’t take nine from zero. So we borrow from our tens place, leaving us with two tens and ten ones. 10 minus nine equals one. And in the tens place, two minus one equals one. And the hundreds place, seven minus seven equals zero. 730 minus 719 equals 11. To finish this book, there are 11 remaining pages.