Wrong by a factor

Six arithmetic slips that produce a wrong figure and look fine — Pakistan

A miscalculation in trading rarely announces itself. The sum runs, a plausible number appears, and the error only surfaces on the statement — because every one of these slips is about units or constants, not about the operations, and a wrong unit still divides perfectly.

All six share a shape: one input carries a different meaning from the one the formula assumed. Points used where pips were meant, a per-side charge counted once, a contract size borrowed from another instrument, a percentage taken from the wrong total, a size rounded upward, a constant read from a page instead of a screen. Each is off by a factor rather than a decimal, and each has a check that takes seconds.

The six, with the damage and the test

The slip	What it does to the answer	The check
Counting points as pips	Out by ten, in either direction	Move one step of the last digit and watch the running result
Counting a commission once	Halves the cost of a round turn	Multiply the quoted per-side figure by two before comparing anything
Borrowing units per lot	Off by whatever the two contracts differ by	Open the specification window for the symbol you are actually trading
Sizing from the wrong total	Every later trade is quietly larger	Decide once whether the share is taken from balance or from equity
Rounding a size upward	Risks more than the amount you agreed to	Round down to the accepted step, always
Trusting a constant from a page	Anything from a rounding to a factor	Read it on your own screen before it enters a sum

Notice that four of the six are lookups gone wrong rather than sums gone wrong. That is why the collection sheet exists: the arithmetic is trivial, and the inputs are where the money is lost.

Two of them, worked out

The tenfold slip

A stop measured as «200» on a five-decimal quote is 200 points, which is 20 pips. Feed 200 into a sizing division built for pips and the denominator is ten times too large, so the size comes out ten times too small. The trade then looks harmless and the plan behind it never gets tested. Feed 20 into a formula expecting points and the mistake runs the other way, which is the expensive direction.
The half-priced round turn

A commission quoted per side and per lot applies at entry and again at exit. Compare a spread-only cost against one side of it and the second structure looks cheaper than it is. The correct comparison prices both structures as money on a full round turn, at the same size, on the same symbol, at the same moment — the method is on the terms page.

Why none of them shows up on the day

A wrong constant does not produce an error message. The ticket accepts the size, the position opens, the running result moves, and everything behaves exactly as a correctly-sized trade would — just at a scale nobody chose. It becomes visible only when a loss arrives and turns out to be several times the figure written on the sheet, at which point the trade gets blamed instead of the input. Running the four reconciliations on a practice account once, at the start, removes the whole category.

What a clean sheet still leaves standing

Losing trades. Correct arithmetic sizes them; it does not prevent them.
A badly chosen stop. Verified units and a wrong level still produce a poor trade.
Fast markets. An exit can fill past the level, making the real loss larger than the computed one.
The overall risk. Trading carries a high risk of losing money, and no amount of checking changes that.

Which slip costs the most?

Whichever one enlarges the size — usually points read as pips in the direction that shrinks the denominator, or a size rounded up.

How do I tell pips from points on my platform?

Count the decimals in the quote. On a five-decimal pair the fourth digit is the pip; the fifth is a point.

Balance or equity for the percentage?

Either, provided it is always the same one. Alternating between them makes every trade a slightly different size than intended.

Is rounding down not wasteful?

It risks slightly less than the plan, which is the direction to be wrong in.

My figures match a guide but not my ticket. Who is right?

The ticket. It uses your constants; a guide uses illustrative ones.

Do these slips exist on a demo too?

Yes — which is precisely why the drills belong there, where being wrong is free.

Is there one habit that prevents most of them?

Reading every constant off your own screen before it enters a sum. Four of the six disappear with it.

How often should the constants be re-read?

Whenever the symbol or the account changes. Contract figures hold; account-level ones do not.

Where each slip gets fixed

Units and counting

Pips, points and the tenfold error.

Count properly

Rounding

What to do with a size the ticket will not take.

See the sizing

Verification

Predict the figure, then let the platform confirm it.

Run the drills

Make every one of these mistakes on virtual money first.

A free demo prints the same figures from the same constants, with nothing to send and no time limit.

Open a free demo at Exness