# Deep Dive: Understanding math and substring formula for custom exports

Expensify Team Posts: 182 Expensify Team
edited February 26

## The more you know - - -

Information about the current user exporting the reports.  This is useful if you need to print the name of the exporter.

To export the email of the currently logged in Expensify user -

• {user:email} would output [email protected] assuming that is the currently logged in Expensify user's email.
• {user:email|frontPart} would output bob assuming that is the currently logged in Expensify user's email.

You are able add formulas that are a math type, allowing you to do arbitrary mathematical equations in your export.

• * — Multiplication {math: 3 * 4} output 12
• / — Division {math: 3 / 4 }output 0.75
• + — Addition {math: 3 + 4 }output
• - — Subtraction {math: 3 - 4 }output -1
• ^ — Exponent {math: 3 ^ 4 } output 81
• sqrt — The square root of a number. {sqrt:64} output 8

• Note - You can also combine the value of any two numerical fields. For example, you can use {math: {expense:tag:glcode} + {expense:category:glcode}} to add the value of the Tag GL code with the Category GL code.

Substring formulas will output a subset of the string in question. It is important to remember that the count starts at 0 not 1.

• `<strong>{expense:merchant|substr:0:4}</strong>` would output `Star` for a merchant named Starbucks. This is because we are telling it to start at position 0 and be of 4 character length.
• `<strong>{expense:merchant|substr:4:5}</strong>` would output `bucks` for a merchant named Starbucks. This is because we are telling it to start at position 4 and be of 5 character length.
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