You are here:

Advanced Math/Amount Needed


Block Wall
Block Wall  
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.


Change inches to feet.
8"8"16" = (2/3)'(2/3)'(4/3)'

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 215 + 211 = 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 1252 = 624 bricks.

Advanced Math

All Answers

Answers by Expert:

Ask Experts


Janet Yang


I can answer questions in Algebra, Basic Math, Calculus, Differential Equations, Geometry, Number Theory, and Word Problems. I would not feel comfortable answering questions in Probability and Statistics or Topology because I have not studied these in depth.


I tutor students (fifth through twelfth grades) and am a Top Contributor on Yahoo!Answers with over 24,000 math solutions.

Co-author of An Outline of Scientific Writing: For Researchers With English as a Foreign Language

I have a Bachelor's degree in Applied Mathematics from the University of California at Berkeley.

Past/Present Clients
George White Elementary School. Homework Help program at the Ridgewood Public Library, Ridgewood, NJ. Individual students.

©2016 All rights reserved.