Tanto si el resultado es exacto como si es aproximado, explica de dónde sale cada número.

It is a fixed structure meaning whether ... or .... It presents two alternatives, and the main statement applies in both cases.

So here, the command explica de dónde sale cada número applies in both situations:

• if the result is exact
• if the result is approximate

Because the full pattern is tanto si + clause + como si + clause.

Spanish repeats si in both parts:

• tanto si el resultado es exacto
• como si es aproximado

That repetition is normal and expected in standard Spanish.

Because in this structure Spanish normally uses the indicative, not the subjunctive.

This is one of the things that can confuse learners, because como si by itself often means as if and then it usually takes the subjunctive:

• Habla como si fuera profesor

But in tanto si ... como si ..., it is a different structure, meaning whether ... or ..., and es is the normal form.

In normal Spanish, it is best to repeat the verb so both parts stay parallel:

• tanto si el resultado es exacto como si es aproximado

Leaving out the second es would sound incomplete or awkward to most speakers in this sentence. As a learner, it is safest to repeat the verb.

Yes. Explica is the tú imperative of explicar.

In textbooks, exercises, and classroom instructions, Spanish often uses this form:

• calcula
• escribe
• explica

It is a direct instruction to one student, in the informal singular.

Because explique would be the formal singular command for usted, while explica is the informal singular command for tú.

In many school materials, especially when speaking directly to the learner, Spanish commonly uses tú commands.

So:

• explica = tell one student informally
• explique = tell one person formally

Literally, it means from where it comes out. Idiomatically, it means where it comes from or how it is obtained.

In a maths or problem-solving context, de dónde sale cada número means you should justify each number:

• what operation produced it
• what step it comes from
• why it appears in the solution

It is a very natural Spanish way to talk about showing your working.

Because it is an interrogative word in an indirect question.

Compare:

• direct question: ¿De dónde sale este número?
• indirect question: Explica de dónde sale cada número

In both cases, dónde keeps the accent.

Without the accent, donde is usually a relative word, as in:

• el lugar donde vive

Because cada is followed by a singular count noun.

So:

• cada número = each number
• not cada números

This is the same idea as English each number, not each numbers.

Because the subject is cada número, and that is grammatically singular.

Even if there are several numbers overall, Spanish treats cada + singular noun as singular, so the verb must also be singular:

• cada número sale
• not cada número salen

Because they agree with resultado, which is masculine singular.

So:

• el resultado exacto
• el resultado aproximado

If the noun were feminine, the adjectives would change:

• la respuesta exacta
• la respuesta aproximada

Not with the same meaning and structure.

After tanto si, standard Spanish normally uses como si, not o:

• tanto si es exacto como si es aproximado

If you want to use o, you would normally choose a different structure, for example:

• sea exacto o aproximado
• ya sea exacto o aproximado

So English whether ... or ... does not map word-for-word here.

Because the sentence begins with a long introductory clause, and then comes the main command.

Structure:

• introductory part: Tanto si el resultado es exacto como si es aproximado
• main instruction: explica de dónde sale cada número

The comma helps separate those two parts clearly. It is natural and standard punctuation in Spanish.