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The Last Decimal / Questions
Twelve questions

The questions, in full

Twelve questions the desk is built to answer, each in a few lines and each traceable to a sample on the site. The page is a starting point as well as a reference.

Sample spec
questions
12
samples
11
answers
direct
arithmetic
shown
the unitThe smallest amount the currency can express. In a two-decimal currency it is 0.01; the increment a stake must take is coarser and published per market.
the directionWhich way each rounding goes: down on a stake and a return, up on a duty and down on a prize. It is a rule, published, and it decides who keeps the fraction.
the volumeOne unit per event is nothing once and a figure at scale: on the samples, two thousand events of the same size retain 60.00 from the digits alone.
Direct answer

The desk answers twelve questions about the smallest unit of money in a gambling account: what the increment is, which way a stake, a return, a balance, a bonus, a conversion, a duty and a price are rounded, what a tail costs at volume, what dust is, what a column that does not add up means, and what rounding cannot change.

The shortest answers

The increment is the step a stake must take, and it is published per market.
A stake is rounded to the increment; sample B rounds down on every request and refuses anything below the minimum.
A return is rounded to the currency's smallest unit; the direction is set by the rules.
A balance is held at full precision and shown at two places, and the two can disagree in either direction.
A bonus credit is rounded down to a unit the operator chooses, and the wagering is computed on the rounded credit.
A conversion rounds down, so its cost is capped at one unit and is largest in percentage terms on the smallest amount.

Read next

The unit and the incrementQuestion 1 and 2 in fullThe volumeQuestion 10 in fullWhat rounding cannot doQuestion 12 in full

The questions, in full

q01

What is the smallest unit of money in a gambling account?

The smallest amount the currency can express: one cent in a two-decimal currency, or one hundred-millionth of a coin in an eight-decimal one. Sample A holds it constant at 0.01 across eight markets.

q02

Is the increment the same as the minimum?

No. The increment is the step a stake must take and the minimum is the smallest stake accepted, and on sample A one market had a 1.00 increment with a 2.00 minimum, so a 1.00 request was refused even though it fitted the step.

q03

Which way is a stake rounded?

The way the rules say. Sample B rounds every request down, so a request of 5.09 places 5.00 and the 0.09 is never staked. Other markets round to the nearest; the page on the stake uses the down rule because it is the common one.

q04

What happens to the fraction that is rounded off?

Nothing is charged and nothing is returned. The fraction was never placed, so it stays in the account as unplaced money, which is why it appears on no statement and is described on this site as a tail rather than a fee.

q05

Why does the balance on screen differ from the balance I can withdraw?

Because the screen shows a rounded rendering of a value held at full precision. On sample D four of eight accounts showed more than they held and three showed less, so a withdrawal of the exact shown figure can be refused.

q06

Is a bonus credit rounded?

Yes. Sample E rounds a 100% credit down to the whole unit and caps it: 836.22 deposited credited 782.00, of which 50.00 was the cap and 4.22 the rounding, and a 0.99 deposit credited nothing.

q07

Is the wagering requirement calculated on the rounded credit?

On the sample, yes: a 49.00 credit carried a 35-times requirement of 1,715.00. The rounding therefore removes 35.00 of wagering as well as 0.50 of credit, because the requirement is built on the credited figure.

q08

Why is rounding a currency conversion so costly on a small amount?

Because the cost is capped at one unit of the second currency. One unit is 1.75% of a 0.50 conversion and 0.00% of a 100.00 one, so the same rule is nearly free at the large end and worth noticing at the small end.

q09

Can a duty and a prize round in opposite directions?

Yes, and on sample G they did: the duty was rounded up on all five stakes and the prize down on all three, which collected 0.0335 across the eight events from two rules that are each defensible on their own.

q10

How much does a rounding cost over many bets?

One unit per event at most. Sample H keeps 50.00 from a thousand stakes of 5.05 and 10.00 from a thousand returns of 7.999999, for 60.00 in total, which is 1.2% of the 5,000.00 of stake turnover that produced it.

q11

Is the displayed price the price that pays?

Not necessarily. Sample R compared eight fractions with their two-decimal displays and found four differences at a stake of 100.00, from 0.28 below to 0.50 above.

q12

Can rounding change whether I win?

No. It decides which unit you receive, never whether a product pays. Its largest figure on this site is about 1.2% of turnover, roughly one eightieth of the cost of a market own margin, and it never moves a losing product into profit.