The addition is one of the four fundamental mathematical operations, the others being subtraction, multiplication, and division. The external height of the box is 12.1 cm.
<h3>What is Addition?</h3>
The addition is one of the four fundamental mathematical operations, the others being subtraction, multiplication, and division. When two whole numbers are added together, the total quantity or sum of those values is obtained.
Given that the internal height of a rectangular box is 10.5cm. The thickness of the bottom is 3/5cm and the thickness of the top is 1cm. Therefore, the external height of the rectangular box is,
Height of rectangular box
= Thickness of bottom + Internal height of the box + Thickness of the top
= 3/5 cm + 10.5 cm + 1 cm
= 0.6cm + 10.5cm + 1cm
= 12.1 cm
Hence, the external height of the box is 12.1 cm.
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