Question

Woody gets 58 rocks to build a dam. He collects them in sacks with 10 rocks in each one of them.
(i) How many sacks are there in all?
(ii) How many sacks are full with rocks?
(iii) How many rocks are left in the last sack?
(iv) Write this in a mathematical statement.

• A. $6,5,2,50=42+8$
• B. $5,6,2,50=58–8$
• C. $5,5,8,58=50+8$
• D. $6,5,8,58=50+8$

Answer 1

The correct option is D $6,5,8,58=50+8$

Say: We have 58 rocks that are packed in sacks of 10 rocks each.

Steps:
$\bullet$ We know that each sack has 10 rocks.
$\bullet$ There are 5 Tens in 58, i.e., $10+10+10+10+10$.
$\bullet$ 5 sacks get filled with 50 rocks.
$\bullet$ 8 rocks are remaining, which will go in the sixth sack.
$\bullet$ Hence, there are a total of 6 sacks, among which 5 are full and the last sack has 8 rocks.
$\bullet$ We can write this as 58 = 50 + 8.
$\bullet$ Hence, Option B is correct.

WB: If required, use the whiteboard to represent the number.

Q: If Woody puts 2 more rocks in the last sack, what will be the new addition statement?
A: $50+8+2=50+10=60$.
Thus, $60=60+0$