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A wall is to be constructed with concrete blocks.

Dimensions of wall- 20' X 16' X 8'

Dimensions of blocks- 8" X 8" X 16"

Calculate number of blocks needed.

Notes: Blocks are actually 3/8" smaller for allowance of mortar. Dimensions are finish dimensions.

I have attached an illustration.

Thanks.

Change inches to feet.

8"×8"×16" = (2/3)'×(2/3)'×(4/3)'

https://www.flickr.com/photos/dwread/14060695882/

Each course of bricks has:

two full rows (blue) that terminate at the outside of the structure

two inside rows (red) that terminate at a brick.

Each course is 2/3 ft high.

8 ft × 1 course/(2/3 ft) = 12 courses

The structure has 12 courses of bricks.

Consider course 1. The full rows are 20 feet long.

20 ft × 1 brick/(4/3 ft) = 15 bricks

Each full row contains 15 bricks

The inside rows are (16 - 2(2/3)) = 44/3 feet long.

44/3 ft × 1 brick/(4/3 ft) = 11 bricks

Each inside row contains 11 bricks

Each odd-numbered course contains 2×15 + 2×11 = 52 bricks.

Similarly, an even-numbered course has 12 bricks in each full row and 14 bricks in each inside row, for a total of 52 bricks.

Since each course contains 52 bricks. the structure uses a total of 12×52 = 624 bricks.

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