# To determine:The check digit of an ISSN that has these initial 7 digits 1553-734

To determine:The check digit of an ISSN that has these initial 7 digits 1553-734
You can still ask an expert for help

## Want to know more about Congruence?

• Questions are typically answered in as fast as 30 minutes

Solve your problem for the price of one coffee

• Math expert for every subject
• Pay only if we can solve it

Yusuf Keller
Formula used:
An ISSN consists of two blocks of four digits. The last digit in the second block is a check digit. This check digit is determined by the congruence
${d}_{8}\equiv 3{d}_{1},+4{d}_{2}+5{d}_{3}+6{d}_{4}+7{d}_{5}+8{d}_{6}+9{d}_{7}±od\left\{11\right\}$
When ${d}_{8}\equiv 10±od\left\{11\right\}$, we use the letter X to represent dg in the code.
Insert the digits of 1553 — 734 into the congruence
${d}_{8}\equiv 3{d}_{1},+4{d}_{2}+5{d}_{3}+6{d}_{4}+7{d}_{5}+8{d}_{6}+9{d}_{7}±od\left\{11\right\}$.
This gives,
${d}_{8}\equiv 3\cdot 1+4\cdot 5+5\cdot 5+6\cdot 3+7\cdot 7+8\cdot 3+9\cdot 4±od\left\{11\right\}$
${d}_{8}\equiv 3+20+25+18+49+24+36±od\left\{11\right\}$
${d}_{8}\equiv 175±od\left\{11\right\}$
${d}_{8}\equiv 10±od\left\{11\right\}$
Hence, the check digit is X.