Video Transcript
Is five plus two plus one less
than, equal to, or greater than 521?
If we look at the two expressions
that we’re comparing in this question, we can see why the question is being
asked. The first expression is an
addition, five plus two plus one. And then, we’re given a number,
521. And if we look at both expressions,
we can see something similar about them. They both contain the same
digits. We can see a five, a two, and a
one. On the right-hand side, our digits
make a three-digit number. The five digit is worth five
hundreds. The two digit is worth two
tens. And the one digit is in the ones
place.
Now, if we look at the five, the
two, and the one in the first expression, we can see that they’re all worth a number
of ones. We’re adding together five ones
plus two ones plus one one. Five plus two plus one equals eight
ones altogether. The value of five plus two plus one
equals eight. And we can see straightaway that
eight is less than 521. Both of our expressions contained
the same digits but to give the digits the same value, they needed to be in the same
columns. And they’re not.
In the first expression, the five,
the two, and the one were all representing a number of ones. But in the second expression, the
five represented five hundreds, the two was in the tens place, and only the one was
in the ones place. Five plus two plus one makes a
total of eight. And eight is less than 521. And so, the correct symbol to use
to compare these two expressions is the one that means is less than.
