Vehicle Checksum Formula

The checksum, also known as the last alphabet of a vehicle license plate, of a bus registration number is derived from the following formula.

Prefix
SG	11 – (5 × 1st No.) – (4 × 2nd No.) – (3 × 3rd No.) – (2 × 4th No.)
SBS	2 – (5 × 1st No.) – (4 × 2nd No.) – (3 × 3rd No.) – (2 × 4th No.)
SMB	9 – (5 × 1st No.) – (4 × 2nd No.) – (3 × 3rd No.) – (2 × 4th No.)
TIB	7 – (5 × 1st No.) – (4 × 2nd No.) – (3 × 3rd No.) – (2 × 4th No.)

SMB Prefix

For example, the British-built Enviro 500 registration plate of SMB5001. Using the above formula for SMB-prefixed plates, we should get a statement like this: 9–(5×5)–(4×0)–(3×0)–(2×1). A quick input of the statement on Google should give a result of -18.

Using the result, mod the number with 19, you will get a number from 0 to 18. You can mod the number by 19 using Google. For the above example where the result is -18, type -18 mod 19 into the Google search bar and it would calculate the answer, 1.
Compare the answer against the table below for the suffix.

Hence, the checksum for SMB5001 is A.

SG Prefix

For example, the 3-Door Double Deck MAN bus registration plate of SG5999. Using the above formula for SG-prefixed plates, we should get a statement like this: 11–(5×5)–(4×9)–(3×9)–(2×9). A quick input of the statement on Google should give a result of -95.

Using the result, mod the number with 19, you will get a number from 0 to 18. You can mod the number by 19 using Google. For the above example where the result is -95, type -95 mod 19 into the Google search bar and it would calculate the answer, 0.
Compare the answer against the table below for the suffix.

Hence the checksum for SG5999 is Z.

Suffix Table(Used for comparison to find the suffix.)

*Letters F, I, N, O, Q, V & W have been omitted.

1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	0
A	B	C	D	E	G	H	J	K	L	M	P	R	S	T	U	X	Y	Z

Alternatively, you may use this checksum calculator created using Google Spreadsheet to get the letters or this checksum calculator tool instead.

For the Google Spreadsheet calculator, go to File then click Make a Copy. The checksum calculator is then for your own use.