📊 Numbers, Data & Metrics
16 exercise sets. Read SLA percentages, performance benchmarks, version numbers, CI pipeline output, sprint data, and business metrics — then use them in sentences.
SLA Uptime Reference — Quick Guide
These figures appear in SLAs and reliability engineering. Know how to read them and say them aloud.
| Uptime % | Allowed Downtime (per year) | How to say it |
|---|---|---|
| 99% | 3.65 days / year | "ninety-nine percent" |
| 99.9% | 8.77 hours / year | "three nines" |
| 99.95% | 4.38 hours / year | "three-and-a-half nines" |
| 99.99% | 52.6 minutes / year | "four nines" |
| 99.999% | 5.26 minutes / year | "five nines" |
- Intermediate
Performance Metrics
Read and talk about p99 latency, throughput, error rates, and response times. "Our p95 is 120ms, but p99 spikes to 800ms under load."
- Intermediate
SLA & Uptime Percentages
"Five nines" (99.999%), calculating downtime budgets, expressing error budget burn rates. Convert percentages to allowed downtime.
- Beginner
Version Numbers & Semver
Reading version numbers like v3.14.2, major/minor/patch meaning, pre-release tags (alpha, beta, rc), and how to say them aloud.
- Beginner
Data Sizes & Units
Bytes, kilobytes, megabytes, gigabytes, terabytes, petabytes — and the difference between MB and MiB. Reading data specs correctly.
- Intermediate
Benchmark Data & Comparisons
"40% faster", "3x throughput improvement", "reduced memory usage by 512MB" — comparative figures in technical English.
- Beginner
Time, Dates & Timestamps
Unix timestamps, UTC, ISO 8601 dates, duration expressions ("within 30 minutes", "over the past 7 days"), timezone references.
- Intermediate
Reading Service Status Updates
Read real-style incident reports, status pages, and maintenance notices. Extract duration, impact, root cause, and next steps.
- Advanced
Writing SLA Language
Choose and evaluate SLA clauses — uptime tiers, incident response times, service credits, and professional support tier descriptions.
- Intermediate
Core Web Vitals
LCP, CLS, INP, FCP, TBT, and Lighthouse scores — read performance reports and communicate results to clients and stakeholders.
- Intermediate
CI Pipeline Summaries
Read build output, discuss failure rates, coverage thresholds (exit codes, test counts, flaky tests) — essential for daily CI/CD work.
- Intermediate
Sprint Burndowns
Read sprint charts and velocity data, discuss scope creep, completion rates, and rollover with the vocabulary used in standups and retros.
- Intermediate
Business Metrics
DAU/MAU ratios, conversion funnels, churn rate, MRR, p99 latency — understand and present product and API metrics to stakeholders.
- Intermediate
Code Coverage Numbers
Read coverage reports, discuss threshold breaches, understand line vs branch coverage, and talk about test debt in professional English.
- Intermediate
CloudWatch & Grafana Dashboards
Read monitoring dashboards and describe what you see: latency spikes, throughput drops, throttle events, concurrency limits — the language of observability.
- Intermediate
Data Pipeline Numbers
Describe pipeline capacity in English: events per second, GB per hour, consumer lag, SLA compliance, and batch job performance metrics.
- Intermediate
Salary & Compensation
Practise discussing compensation professionally: understanding total comp, RSU vesting, comparing offers, stating salary expectations, and negotiating a raise.