Multiply then divide — Math

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$Multiply then divide$

Multiply then divideMultiply then divide

Math · Reads onchain state

Multiplies two values and divides by a third in one step, rounding up or down. Dividing after the multiply avoids the truncation of a separate divide-then-multiply, so fixed-point ratios like utilization stay wei-exact, while round-up matches protocol share math that rounds debt up. The x × y intermediate is a checked 256-bit product: the call reverts if it overflows uint256, and reverts on z = 0. Reach for it to convert an amount across a price or rate, such as collateral times price divided by WAD, or to scale a balance by a share ratio without losing precision.

Use in App

Card: Buy $50 WBTC With USDC Once a Week

20actions

1·Repeat
This plug is rate limited to run at most once every two weeks, so it can fire only a single time per fortnight.
2·Get constant
A named constant WAD equal to 1e18 is loaded for later math involving 18 decimal scaling.
3·Calculate
Fifty is multiplied by the WAD constant, scaling the number fifty up to 18 decimals.
4·Get constant
The basis-point denominator of 10,000 is loaded as a named constant.
5·Calculate
From the scaled fifty in slot 3.0, fifty is subtracted, producing that scaled value minus a plain fifty.
6·Calculate proportional value
A proportion is taken: 10,000 basis points of the WAD value, which is the whole of it since 10,000 basis points equals one hundred percent.
7·Get price
The latest Chainlink price of BTC in USD is read, normalized to 18 decimals.
8·Calculate
Ten is raised to the power of eight, giving the factor for eight decimals.
9·Multiply then divide
Multiplying the value from slot 5.0 by the BTC price and dividing by the value in slot 6.7, rounding down, computes a scaled expected amount.
10·Get token balance
The socket's own WBTC balance is read before any swap happens.
11·Get address
The solver address is held as a named value for use as the transfer destination.
12·Calculate
Ten is raised to the power of six, giving the factor for six decimals matching USDC.
13·Calculate
Fifty is multiplied by the six-decimal factor, producing fifty USDC in base units.
14·Transfer tokens
That fifty USDC is transferred to the balance-holder address referenced from slot 10.0.
15·Get solution
The solver takes the transferred tokens, routes them, and the outcome is verified.
16·Get token balance
After routing, the socket's WBTC balance is read again.
17·Calculate
Subtracting the pre-swap WBTC balance from the post-swap balance yields the WBTC actually received.
18·Predicate
A requirement enforces that the WBTC received is greater than or equal to the expected amount from slot 8.0, reverting otherwise.
19·End block
The open block is closed here.
20·Bubble
The WBTC received amount is surfaced as the output of this plug.