2. 1. Rounding tenths
c) 2.99 = 3
We’ve got to round 2.99 to tenths.
On the tenths place we’ve got a 9. Beyond it, on the
hundreths place, we find a 9, which is a biggest number
than 5.
That’s the reason why we round up the hall number to 3,
because when we round up the 9 of the tenths place, we
automatically got a different number in the ones place.
So finally, we round up 2.99 to 3.
3. 2. Rounding hundreths
b) 1.278 = 1.28
We’ve got to round 1.278 to hundreths.
On the hundreths place we’ve got a 7. Beyond it, on the
thousandths place, we’ve got a 8, which is a biggest
number than 5.
So, on the hundreths place we round up from 7 to 8.
So, the final rounding number is 1.28.
4. 3. Powers
b) 10⁴ · 10² = 10⁶
In numbers with the same base, we multiplicate powers
just adding the exponents.
So, we have to add the first exponent, 4, and the second
one, which is 2.
2 + 4 = 6
The result is 10 to the power 6.
5. 4. Calculate
a) 5⁴ · 2⁴ = 10⁴
We’ve only got to multiply the bases because the
exponents are the same.
That’s why we multiply 2 times 5.
2 x 5 = 10
The result is 10 to the power 4.
6. 5. Least common multiple
a) 1020, 440 and 840 = 157080
To find the least common multiple of these three numbers,
we have to decompose them and choose all the numbers,
and the biggest common number between them.
In this case, 1020 equals to 17 · 5 · 3 · 2²; 440 equals to 11
· 5 · 2³; and 840 equals to 7 · 5 · 3 · 2³.
So, the least common multiple is 17 · 11 · 7 · 5 · 3 · 2³,
which equals to 157080.
