TY  - BOOK
AU  - Eastaway, Rob
TI  - Maths on the back of an envelope: clever ways to (roughly) calculate anything
SN  - 9780008324582
U1  - 512 EAS 
PY  - 2019///
CY  - London
PB  - Harper Collins Publishers
KW  - Arithmetic
KW  - Mathematics
KW  - Popular works
ER  -