Logarithm dominoes – what’s the base?
Cut out the 24 dominoes below. Match them into one continuous loop by finding the value of each
base (x).
3
2
log x 243   5
5
27
125
5 1
log x   
3 2
3
5
log x
8
 1 
log x    2
 49 
25
9
2
4
log x    
3
9
1
2
log x 2  
1
3
1
8
 64 
log x    3
 27 
log x 16  
4
3
 2    21
3
log x 0.000001  6
1
2
 64 
log x    6
 27 
3
4
 1
log x    2
 25 
3
log x 32  5
2
log x 625   8
27
8
log x 125   6
1
3
 1
log x    3
 64 
4
 8 
log x    3
 27 
1
5
log x 4   4
0.1
 1
log x    8
 16 
2
3
5
log x    1
3
5
3
log x    1
7
2
log x 9   4
1
7
 16 
log x    4
 81 
3
7
3 1
log x   
5 3
3
2
log x 243   5
© www.teachitmaths.co.uk 2013
20633
Page 1 of 2
Logarithm dominoes – what’s the base?
Teaching notes
Students should be able to apply the basic definition of a logarithm to find the base when
given the argument and answer:
if logbx = y then by = x
Answers (reading down the page)
3
log x 32  5
3
5
2
logx 9   4
1
2
3
logx 0.000001  6
1
8
0.1
 1
logx    8
 16 
3
4
2
logx 625   8
5
5
logx 16  
4
3
3
7
logx
 2    21
logx 2  
1
3
 64 
logx    3
 27 
 1
log x    2
 25 
3
logx    1
7
3 1
log x   
5 3
 1 
logx    2
 49 
 16 
logx    4
 81 
27
125
3
2
log x 243   5
27
8
logx 125   6
1
3
 1
logx    3
 64 
 8 
logx    3
 27 
1
5
logx 4   4
1
2
 64 
logx    6
 27 
5
logx    1
3
3
2
logx 243   5
8
1
7
4
2
3
© www.teachitmaths.co.uk 2013
25
9
20633
5 1
log x   
3 2
2
4
logx    
3
9
Page 2 of 2